diff --git a/zh_TW.Big5/books/handbook/disks/chapter.sgml b/zh_TW.Big5/books/handbook/disks/chapter.sgml index 0fff7c1603..33a1c33aa9 100644 --- a/zh_TW.Big5/books/handbook/disks/chapter.sgml +++ b/zh_TW.Big5/books/handbook/disks/chapter.sgml @@ -1,4019 +1,3957 @@ 儲存設備篇 概述 本章涵蓋如何在 FreeBSD 下使用碟片裝置 - 譯註：雖然有些設備沒有『碟片』，例如 USB 隨身碟， - 不過在此仍把 Disk 譯為『碟片裝置』。此外，為方便起見， - 後文所有的 Disk 都譯為『硬碟』。 - 包含 memory-backed disk (用記憶體作為硬碟使用)、跨網路使用的硬碟、 - 標準 SCSI/IDE 硬碟、USB 介面的設備等。 + + 譯註：雖然有些設備沒有『碟片』，例如 USB 隨身碟， + 不過在此仍把 Disk 譯為『碟片裝置』。此外，為方便起見， + 後文所有的 Disk 都譯為『磁碟』。 + 包含 memory-backed disk (用記憶體作為磁碟使用)、跨網路使用的磁碟、 + 標準 SCSI/IDE 磁碟、USB 介面的設備等。 閱讀本章後，您裝學會： - FreeBSD 如何描述資料在硬碟上的劃分情形 + FreeBSD 如何描述資料在磁碟上的劃分情形 (partition 和 slices)。 - 如何在系統上加入硬碟 + 如何在系統上加入磁碟 如何設定 &os; 來使用 USB 裝置。 如何設定虛擬檔案系統 (virtual file systems), - 例如 memory disks (用記憶體作為硬碟使用)。 + 例如 memory disks (用記憶體作為磁碟使用)。 - 如何用 quota 來限制硬碟空間的使用。 + 如何用 quota 來限制磁碟空間的使用。 - 如何對硬碟加密以應付攻擊。 + 如何對磁碟加密以應付攻擊。 如何在 FreeBSD 下建立、燒錄 CD 和 DVD。 各種不同的備份設備。 如何使用 FreeBSD 提供的備份工具。 如何備份到軟碟。 什麼是 snapshots ，且如何有效率地使用之。 在閱讀之前，您應該： - 知道如何配置、安裝新的 FreeBSD 核心。 + 知道如何設定、安裝新的 FreeBSD kernel。 (). 裝置名稱 下面是 FreeBSD 支援的儲存媒體列表，及它們對應的裝置名稱。 命名規則 裝置類型 裝置名稱 - IDE 硬碟機 + IDE 磁碟機 ad IDE 光碟機 acd - SCSI 硬碟機和 USB 碟 + SCSI 磁碟機和 USB 碟 da SCSI 光碟機 cd 非標準規格光碟機 Mitsumi 光碟機用 mcd， Sony 光碟機用 scd。 軟碟機 fd SCSI 碟帶機 sa IDE 碟帶機 ast Flash 磁碟機 &diskonchip; Flash 磁碟機用 fla RAID 磁碟機 &adaptec; AdvancedRAID 用aacd， &mylex; 用 mlxd 和 mlyd， AMI &megaraid; 用 amrd， Compaq Smart RAID 用 idad， &tm.3ware; RAID 用 twed。
David O'Brien Originally contributed by - 新增硬碟 + 新增磁碟 disk adding - 假設我們想新增 SCSI 硬碟到一臺原先只有一顆硬碟的機器上， - 首先將電腦關機，依製造商的指示將硬碟裝上去， - 詳細的操作方式請參考製造商的說明文件。 + 假設我們想新增 SCSI 磁碟到一臺原先只有一顆磁碟的機器上， + 首先將電腦關機，依製造商的指示將磁碟裝上去， + 詳細的操作方式請參考製造商的說明文件。 - 安裝好硬碟後，用 root 登入系統， - 看一下 /var/run/dmesg.boot 以確認系統是否抓到新硬碟。 - 繼續剛才的範例，新增的硬碟會是 da1， - 假設我們想將它掛載到 /1 這個位置 - (如果您新增的是 IDE 硬碟的話，請用 - ad1)。 + 安裝好磁碟後，用 root 登入系統， + 看一下 /var/run/dmesg.boot 以確認系統是否抓到新磁碟。 + 繼續剛才的範例，新增的磁碟會是 da1， + 假設我們想將它掛載到 /1 這個位置 + (如果您新增的是 IDE 磁碟的話，請用 ad1)。 partitions slices fdisk FreeBSD 為了在 IBM-PC 相容電腦上執行， - 必須配合 PC BIOS partition，因此和傳統的 BSD partition 有很大的不同。 - 在 PC 裡硬碟最多可以有四筆 BIOS partition 資訊(亦即最多可分割成四個 - partition)。如果這個硬碟打算全部讓 FreeBSD 使用，可選擇 - dedicated 模式， - 不然的話 FreeBSD 必須置身於其中一個 PC BIOS partition 中。 - 在 FreeBSD 裡，PC BIOS partition 稱為 slice， - 這是為了不要和傳統的 BSD partition 搞混了 - 譯註：基於相同的理由， - 現在 BSD partition 常稱為 BSD label，或簡稱 label。 - 不論是完全由 FreeBSD 使用的硬碟，還是安裝了其它作業系統的硬碟， - 您都可以使用 slice。這樣的好處是，其它非 FreeBSD 作業系統的 - fdisk 工具可以順利操作。 - - 如果使用 slice，這個新增的硬碟會是 - /dev/da1s1e。可以這樣來解讀它：SCSI 硬碟、 - unit number 1(第二個 SCSI 硬碟)、slice 1(第一個 PC BIOS partition)、 - 及 e BSD partition。在 dedicated 模式的話， - 新硬碟則是 /dev/da1e。 - - 因為 &man.bsdlabel.8; - 用 32-bit 整數來儲存 sector(磁區) 數， - 因此限制一個硬碟最大只能有 2^32-1 個 sector，亦即 2TB 的空間。 - 而 &man.fdisk.8; 的格式容許起始 sector 編號不超過 2^32-1， - 長度也不超過 2^32-1，因此 partition 最大空間是 2TB，而硬碟最大是 4TB。 - &man.sunlabel.8; 則限制 partition 最大是 2TB，硬碟最多可有 8 個 partition， - 因此最大是 16TB。如果要使用更大的硬碟，請使用 &man.gpt.8;。 + 必須配合 PC BIOS partition，因此和傳統的 BSD partition 有很大的不同。 + 在 PC 裡磁碟最多可以有四筆 BIOS partition 資訊(亦即最多可分割成四個 + partition)。如果這個磁碟打算全部讓 FreeBSD 使用，可選擇 + dedicated 模式， + 不然的話 FreeBSD 必須置身於其中一個 PC BIOS partition 中。 + 在 FreeBSD 裡，PC BIOS partition 稱為 slice， + 這是為了不要和傳統的 BSD partition 搞混了。 + 譯註：基於相同的理由， + 現在 BSD partition 常稱為 BSD label，或簡稱 label。 + 不論是完全由 FreeBSD 使用的磁碟，還是安裝了其它作業系統的磁碟， + 您都可以使用 slice。這樣的好處是，其它非 FreeBSD 作業系統的 + fdisk 工具可以順利操作。 + + 如果使用 slice，這個新增的磁碟會是 + /dev/da1s1e。可以這樣來解讀它：SCSI 磁碟、 + unit number 1(第二個 SCSI 磁碟)、slice 1(第一個 PC BIOS partition)、 + 及 e BSD partition。在 dedicated 模式的話， + 新磁碟則是 /dev/da1e。 + + 因為 &man.bsdlabel.8; 是用 32-bit 整數來儲存 sector(磁區) 數， + 因此限制一個磁碟最大只能有 2^32-1 個 sector，亦即 2TB 的空間。 + 而 &man.fdisk.8; 的格式容許起始 sector 編號不超過 2^32-1， + 長度也不超過 2^32-1，因此 partition 最大空間是 2TB，而磁碟最大是 4TB。 + &man.sunlabel.8; 則限制 partition 最大是 2TB，磁碟最多可有 8 個 + partition，因此最大是 16TB。 如果要使用更大的磁碟，請使用 + &man.gpt.8;。 使用 &man.sysinstall.8; sysinstall - 新增硬碟 + 新增磁碟 su 操作 <application>Sysinstall</application> - 透過 sysinstall - 的選單介面，您可以輕易為硬碟分割 BIOS partition(slice) - 和 BSD patition。您必須以 root 身份使用 sysinstall， - 要嘛用 root 登入，要嘛用 su 切換到 root。 - 執行 sysinstall 後，選 Configure - ，在 FreeBSD Configuration Menu 裡移到 - Fdisk 選項， + 透過 sysinstall 的選單介面， + 可以輕易為磁碟分割 BIOS partition(slice) 和 BSD patition。 + 必須以 root 身份使用 sysinstall， + 要嘛用 root 登入，要嘛用 su 切換到 root。 + 執行 sysinstall 後，選 + Configure，在 + FreeBSD Configuration Menu 裡移到 + Fdisk 選項。 <application>fdisk</application> Partition 編輯器 + 在 fdisk 裡，按下 - A 表示整個硬碟都給 FreeBSD 使用。 - 接著會提示您『是否要相容其它的作業系統』，回答 YES。 - 按 W 會將這些改變立即寫入硬碟， - 再按 q 可以離開 FDISK 編輯器。 - 接下來會問您要將 Master Boot Record 安裝於何處， - 由於現在是新增硬碟，表示作業系統已經裝在別的硬碟上了，所以可以 - None 就行了。 + A 表示整個磁碟都給 FreeBSD 使用。 + 接著會提示您『是否要相容其它的作業系統』，回答 + YES。 按 W + 會將這些改變立即寫入磁碟，再按 q 可以離開 + FDISK 編輯器。 接下來會問您要將 Master Boot Record + 安裝於何處，由於現在是新增磁碟，表示作業系統已經裝在別的磁碟上了， + 所以可以選 None 就行了。 - Disk Label Editor(硬碟 Label 編輯器) + Disk Label Editor(磁碟 Label 編輯器) BSD partitions - 接著請關閉 sysinstall， - 再重開一次。照著上一節的指示，不過這次改選 Label - 進入 Disk Label Editor，在此您可以編輯傳統的 - BSD partition。一個硬碟(或著一個 slice) 最多可切分成 8 個 BSD partition， - 依序用 a-h 來表示。 - 有些字母有特別的意義，a partition 表示這是 - root partition(根分割區，/)， - 因此只有安裝系統的硬碟(例如用來開機的硬碟) 有 - a partition。b partition - 表示這是 swap partitions(交換分割區)，每個硬碟上都可以有交換分割區。 - c partition - 用來表示整個硬碟(如果使用 dedicated mode 的話) - 或整個 slice。其它的字母則用來表示普通的 BSD partition。 + 接著請關閉 sysinstall，再重開一次。 + 照著上一節的指示，不過這次改選 Label + 進入 Disk Label Editor，在此您可以編輯傳統的 + BSD partition。 一個磁碟(或著一個 slice) 最多可切分成 8 個 + BSD partition，依序用 a-h 來表示。 + 有些字母有特別的意義，a partition 表示這是 + root partition(根分割區，/)， + 因此只有安裝系統的磁碟(例如用來開機的磁碟) 有 + a partition。 b partition + 表示這是 swap partitions(交換分割區)，每個磁碟上都可以有 swap。 + c partition 用來表示整個磁碟(如果使用 dedicated + mode 的話)或整個 slice。 其它的字母則用來表示普通的 BSD partition + 。 sysinstall 的 - Label editor(硬碟 Label 編輯器) 偏好用 e - 來表示非 root、也非 swap 的分割區 - 譯註：老實說我看不懂這句指的是什麼？原文是 + Label editor(磁碟 Label 編輯器) 偏好用 e + 來表示非 root、也非 swap 的分割區 + + 譯註：老實說我看不懂這句指的是什麼？原文是 sysinstall Label editor - favors the e partition for non-root, - non-swap partitions. 在 Label editor 裡， - 按 C 可以新增一個檔案系統(BSD label)， - 它會問您這是一個 FS(file system，檔案系統) 或是 swap(交換分割區)， - 選擇 FS 接著輸入要掛載的位置 - (例如 /mnt)。如果系統安裝完後才新增硬碟， - sysinstall 不會幫您把這筆掛載資料加入 - /etc/fstab，所以掛載的位置不太重要。 - - 當您準備好將新的 label 寫入硬碟、建立檔案系統， - 按 W 即可。如果出現在什麼錯誤， - sysinstall 可能無法幫您掛載這個新分割區。 - 結束 Label Editor、結束 sysinstall 就行了。 + favors the e partition for non-root, + non-swap partitions. + 在 Label editor 裡，按 C + 可以新增一個檔案系統(BSD label)，它會問您這是一個 FS(file system + ，檔案系統) 或是 swap(交換分割區)，選擇 FS + 接著輸入要掛載的位置(例如 /mnt)。 + 如果系統安裝完後才新增磁碟，sysinstall + 不會幫您把這筆掛載資料加入 /etc/fstab， + 所以掛載的位置不太重要。 + + 當您準備好將新的 label 寫入磁碟、建立檔案系統，按 + W 即可。如果出現在什麼錯誤， + sysinstall 可能無法幫您掛載這個新分割區。 + 結束 Label Editor、結束 sysinstall + 就行了。 完成 最後要做的是編輯 /etc/fstab， - 加入您新增的分割區資訊。 + 加入您新增的分割區資訊。 使用命令列工具 使用 Slices(BIOS partitions) - 這種模式能讓您的硬碟分割區與其它作業系統的 + 這種模式能讓您的磁碟分割區與其它作業系統的 fdisk 工具和平共處，因此我們建議您使用 slice 模式。 如果您一定要使用 dedicated 模式， 您得有個好理由！ - 譯註：如果您自始至終都不打算將這個硬碟用於 FreeBSD - 之外的作業系統，那可以算是個好理由。不過就算如此， - 用 slice 模式也沒什麼壞處就是了:-)。 + + 譯註：如果您自始至終都不打算將這個磁碟用於 FreeBSD + 之外的作業系統，那可以算是個好理由。不過就算如此， + 用 slice 模式也沒什麼壞處就是了:-)。 &prompt.root; dd if=/dev/zero of=/dev/da1 bs=1k count=1 -&prompt.root; fdisk -BI da1 # 初始您的硬碟。 +&prompt.root; fdisk -BI da1 # 初始您的磁碟。 &prompt.root; bsdlabel -B -w -r da1s1 auto # 建立 bsdlabel。 &prompt.root; bsdlabel -e da1s1 # 編輯 bsdlabel 以新增 label。 &prompt.root; mkdir -p /1 &prompt.root; newfs /dev/da1s1e # 如果您新增了多個 label，對每個 label 重覆這個步驟。 &prompt.root; mount /dev/da1s1e /1 # 掛載這些新 label。 &prompt.root; vi /etc/fstab # 在 /etc/fstab 加入適當的資訊。 - 如果您新增的是 IDE 硬碟，將 da - 改成 da 即可 - 譯註：da 是 direct access。。 + 如果您新增的是 IDE 磁碟，將 da + 改成 ad 即可 + + 譯註：da 是 direct access (disk) 的縮寫； + ad 是 ata disk 的縮寫。。 Dedicated OS/2 - 如果您不打算將新硬碟用於其它的作業系統， + 如果您不打算將新磁碟用於其它的作業系統， 您可以使用 dedicated 模式。注意： Microsoft 的作業系統認不得這個模式，不過也不會去破壞它； 然而 IBM 的 &os2; 就沒那麼好心了，它會去調整所有它不認得的分割區 - 譯註：我對這句的意思沒什麼信心，原文是 IBM's &os2; however, - will appropriate any partition it finds which it does - not understand.。 + + 譯註：我對這句的意思沒什麼信心，原文是 IBM's &os2; however, + will appropriate any partition it finds which it + does not understand.。 &prompt.root; dd if=/dev/zero of=/dev/da1 bs=1k count=1 &prompt.root; bsdlabel -Brw da1 auto &prompt.root; bsdlabel -e da1 # 建立 `e' partition。 &prompt.root; newfs -d0 /dev/da1e &prompt.root; mkdir -p /1 &prompt.root; vi /etc/fstab # 新增一筆 /dev/da1e 的資訊。 &prompt.root; mount /1 另一種方法： &prompt.root; dd if=/dev/zero of=/dev/da1 count=2 &prompt.root; bsdlabel /dev/da1 | bsdlabel -BrR da1 /dev/stdin &prompt.root; newfs /dev/da1e &prompt.root; mkdir -p /1 &prompt.root; vi /etc/fstab # 新增一筆 /dev/da1e 的資訊。 &prompt.root; mount /1 RAID 軟體 RAID Christopher Shumway Original work by Jim Brown Revised by RAIDsoftware RAIDCCD 連接式磁碟裝置驅動程式(CCD, Concatenated Disk Driver) 設定 對大容量儲存設備而言，最關鍵的要素乃是速度、可靠性及價格。 - 然而這三者往往難以兼顧：快速可靠的設備通常很貴； - 而降低成本通常也犧牲了速度或可靠性。 + 然而這三者往往難以兼顧：快速可靠的設備通常很貴； + 而降低成本通常也犧牲了速度或可靠性。 - 接下來要介紹的系統，價格是最重要的考量，接下來是速度，最後才是可靠性。 - 順序如此是因為資料傳輸的速度最終取決於網路，而儘管可靠性十分重要， - 卻有簡單的取代方案：將資料完整備份於 CD-R 中。 + 接下來要介紹的系統，價格是最重要的考量，接下來是速度， + 最後才是可靠性。 順序如此是因為資料傳輸的速度最終取決於網路， + 而儘管可靠性十分重要，卻有簡單的取代方案： + 將資料完整備份於 CD-R 中。 - 選擇大容量儲存設備方案時，首先要定義您的需求。如果您重視速度或可靠性 - 甚於價格，接下來的介紹恐非您所需。 + 選擇大容量儲存設備方案時，首先要定義您的需求。 + 如果您重視速度或可靠性甚於價格，接下來的介紹恐非您所需。 安裝硬體 除了系統磁碟外，下面介紹的 CCD 磁碟陣列將使用到三顆 30GB、 - 5400 RPM 的 Western Digital IDE 磁碟，以提供約 90GB 的儲存空間。 - 最理想的情況是每個磁碟由獨立使用的排線連接獨立使用的 IDE 控制器， - 不過為了降低成本，利用 jumper 設定磁碟，使每個 IDE 控制器可連接 - 一個主磁碟加一個副磁碟，如此可不必加裝額外的 IDE 控制器。 + 5400 RPM 的 Western Digital IDE 磁碟，以提供約 90GB 的儲存空間。 + 最理想的情況是每個磁碟由獨立使用的排線連接獨立使用的 IDE 控制器， + 不過為了降低成本，利用 jumper 設定磁碟，使每個 IDE 控制器可連接 + 一個主磁碟加一個副磁碟，如此可不必加裝額外的 IDE 控制器。 開機後，BIOS 應該設定成自重偵測磁碟。更重要的是 FreeBSD 應該 - 要偵測到它們： + 要偵測到它們： ad0: 19574MB <WDC WD205BA> [39770/16/63] at ata0-master UDMA33 ad1: 29333MB <WDC WD307AA> [59598/16/63] at ata0-slave UDMA33 ad2: 29333MB <WDC WD307AA> [59598/16/63] at ata1-master UDMA33 ad3: 29333MB <WDC WD307AA> [59598/16/63] at ata1-slave UDMA33 - 如果 FreeBSD 沒有偵測到所有磁碟，請確認 jumper 都設定正確。 - 許多 IDE 磁碟可以設定成 Cable Select(根據排線位置決定)， - 這並非 master(主磁碟) 或 slave(副磁碟)。請參閱磁 - 碟的說明文件以正確設定 jumper。 + + 如果 FreeBSD 沒有偵測到所有磁碟，請確認 jumper 都設定正確。 + 許多 IDE 磁碟可以設定成 Cable Select + (根據排線位置決定)，這並非 master(主磁碟) + 或 slave(副磁碟)。 請參閱磁碟的說明文件以正確設定 jumper + 。 接下來，考慮如何將它們變成檔案系統的一部份。您可以參考 - &man.vinum.8;() 及 &man.ccd.4。 - 在此我們選擇 &man.ccd.4; 。 + &man.vinum.8;() 及 &man.ccd.4。 + 在此我們選擇 &man.ccd.4;。 - Setting Up the CCD + 設定 CCD - The &man.ccd.4; driver allows you to take - several identical disks and concatenate them into one - logical file system. In order to use - &man.ccd.4;, you need a kernel with - &man.ccd.4; support built in. - Add this line to your kernel configuration file, rebuild, and - reinstall the kernel: + &man.ccd.4; 可以將多個磁碟接起來成為一個大磁碟。要使用 + &man.ccd.4;，您的 kernel 需要支援 &man.ccd.4;。將這行加入到 + kernel 設定檔，並重編、重安裝 kernel： device ccd - The &man.ccd.4; support can also be - loaded as a kernel loadable module. + 也可以載入 kernel 動態模組來支援 &man.ccd.4;。 - To set up &man.ccd.4;, you must first use - &man.bsdlabel.8; to label the disks: + 使用 &man.ccd.4; 請先用 &man.bsdlabel.8; 來初始磁碟： bsdlabel -r -w ad1 auto bsdlabel -r -w ad2 auto bsdlabel -r -w ad3 auto - This creates a bsdlabel for ad1c, ad2c and ad3c that - spans the entire disk. + 上述指令會建立 ad1c， + ad2c 和 ad3c， + 這些 bsdlabel 都使用了整個磁碟。 - The next step is to change the disk label type. You - can use &man.bsdlabel.8; to edit the - disks: + 下一步是修改 label type，同樣用 &man.bsdlabel.8; 來處理： bsdlabel -e ad1 bsdlabel -e ad2 bsdlabel -e ad3 - This opens up the current disk label on each disk with - the editor specified by the EDITOR - environment variable, typically &man.vi.1;. + 這個指令會打開一個編輯器(預設是 &man.vi.1;，可以用 + EDITOR 環境變數來指定其它編輯器)，並將目前磁碟的 label + 資訊顯示在該編輯器裡。 - An unmodified disk label will look something like - this: + 一個還未變動過的磁碟 label 資訊看起來會像這樣： 8 partitions: # size offset fstype [fsize bsize bps/cpg] c: 60074784 0 unused 0 0 0 # (Cyl. 0 - 59597) - Add a new e partition for &man.ccd.4; to use. This - can usually be copied from the c partition, - but the must - be 4.2BSD. The disk label should - now look something like this: + 在此我們要新增一個 e partition 給 + &man.ccd.4; 使用。 通常複製 c partition 那一行， + 再把 那一行改成 + 4.2BSD 就可以了。 + 改完之後看起來應該會像這樣： 8 partitions: # size offset fstype [fsize bsize bps/cpg] c: 60074784 0 unused 0 0 0 # (Cyl. 0 - 59597) e: 60074784 0 4.2BSD 0 0 0 # (Cyl. 0 - 59597) - Building the File System + 建立檔案系統 - Now that you have all the disks labeled, you must - build the &man.ccd.4;. To do that, - use &man.ccdconfig.8;, with options similar to the following: + 現在所有的磁碟都已經建好 bsdlabel 了，可以開始建立 &man.ccd.4;。 + 用 &man.ccdconfig.8; 來建立 &man.ccd.4;，參考下面的指令： ccdconfig ccd0 32 0 /dev/ad1e /dev/ad2e /dev/ad3e - The use and meaning of each option is shown below: + 每個參數的作用如下： - The first argument is the device to configure, in this case, - /dev/ccd0c. The /dev/ - portion is optional. + 第一個參數是要設定的裝置名稱，在這個例子裡是 + /dev/ccd0c。其中 /dev/ + 可有可無。 - The interleave for the file system. The interleave - defines the size of a stripe in disk blocks, each normally 512 bytes. - So, an interleave of 32 would be 16,384 bytes. + 「interleave」的大小。所謂 interleave 是指一排磁碟區塊 + (disk block)的大小，通常以 512 bytes 為單位，所以 interleave + 設為 32 即為 16,384 bytes。 - Flags for &man.ccdconfig.8;. If you want to enable drive - mirroring, you can specify a flag here. This - configuration does not provide mirroring for - &man.ccd.4;, so it is set at 0 (zero). + &man.ccdconfig.8; 設定模式的參數。如果您打算啟用磁碟鏡設 + (drive mirroring)，您可以在此指定參數。這個例子沒有使用鏡設， + 所以設成 0。 - The final arguments to &man.ccdconfig.8; - are the devices to place into the array. Use the complete pathname - for each device. + &man.ccdconfig.8; 最後的參數是要加入到陣列的所有磁碟。 + 請使用完整的路徑。 - After running &man.ccdconfig.8; the &man.ccd.4; - is configured. A file system can be installed. Refer to &man.newfs.8; - for options, or simply run: + 執行 &man.ccdconfig.8; 之後，&man.ccd.4; + 已設定完成可供建立檔案系統。 請參考 &man.newfs.8; 或輸入： newfs /dev/ccd0c - Making it All Automatic + 讓一切自動完成 - Generally, you will want to mount the - &man.ccd.4; upon each reboot. To do this, you must - configure it first. Write out your current configuration to - /etc/ccd.conf using the following command: + 通常您會希望每次開機時都能自動掛上(mount) &man.ccd.4;。 + 用下面的指令將您目前的設定寫入 /etc/ccd.conf + ： ccdconfig -g > /etc/ccd.conf - During reboot, the script /etc/rc - runs ccdconfig -C if /etc/ccd.conf - exists. This automatically configures the - &man.ccd.4; so it can be mounted. + 如果 /etc/ccd.conf 存在，每次開機時 + /etc/rc 都會執行 ccdconfig -C + 。 如此便可自動設定 &man.ccd.4; 以便之後掛上(mount)檔案系統。 + - If you are booting into single user mode, before you can - &man.mount.8; the &man.ccd.4;, you - need to issue the following command to configure the - array: + 如果您開機時選擇進入單人模式(single mode)，在掛上 + (&man.mount.8;) &man.ccd.4; 的檔案系統之前您得先執行設定的指令： + ccdconfig -C - To automatically mount the &man.ccd.4;, - place an entry for the &man.ccd.4; in - /etc/fstab so it will be mounted at - boot time: + 要在每次開機時自動掛上(mount) &man.ccd.4;，請在 + /etc/fstab 加入 &man.ccd.4;： + /dev/ccd0c /media ufs rw 2 2 - The Vinum Volume Manager + Vinum 容量管理系統 RAIDsoftware RAID Vinum - The Vinum Volume Manager is a block device driver which - implements virtual disk drives. It isolates disk hardware - from the block device interface and maps data in ways which - result in an increase in flexibility, performance and - reliability compared to the traditional slice view of disk - storage. &man.vinum.8; implements the RAID-0, RAID-1 and - RAID-5 models, both individually and in combination. + Vinum 容量管理系統(以下簡稱 Vinum) 可視為一種虛擬磁碟。 + 它將區塊裝置(block device) 的介面與對應資料的方式切割開來，比起原本 + slice 劃分的磁碟，Vinum 可增加了彈性、效能和穩定度 + 譯註：原文這裡是用「和」，但要視實際使用方式而定。 + 例如用 RAID-0 就不會增加穩定度 :)。 + &man.vinum.8; 實作了 RAID-0、RAID-1 和 RAID-5 等模組， + 它們都可以單獨使用，也可以互相搭配使用。 - See for more - information about &man.vinum.8;. + 請見 以參考更多關於 + &man.vinum.8; 的資訊。 - Hardware RAID + 硬體 RAID RAID hardware - FreeBSD also supports a variety of hardware RAID - controllers. These devices control a RAID subsystem - without the need for FreeBSD specific software to manage the - array. - - Using an on-card BIOS, the card controls most of the disk operations - itself. The following is a brief setup description using a Promise IDE RAID - controller. When this card is installed and the system is started up, it - displays a prompt requesting information. Follow the instructions - to enter the card's setup screen. From here, you have the ability to - combine all the attached drives. After doing so, the disk(s) will look like - a single drive to FreeBSD. Other RAID levels can be set up - accordingly. - - + FreeBSD 也支援許多硬體 RAID 控制器。 + 這些控制器自行掌控一個小型的 RAID 系統， + 因此不需要特定軟體來管理。 + + 透過控制器上的 BIOS 幾乎能控制所有的操作。 + 接下來將簡單介紹如何設定 Promise IDE + RAID 控制卡。首先確認控制卡已安裝，接著開機。 + 它應該會提示一些資訊譯註：例如按 F1 可以進入控制卡 + BIOS 之類的資訊。。依指示進入控制卡的設定畫面， + 從這裡您可以將全部的硬體結合成一個大磁碟。完成之後，FreeBSD + 將只會看到這個大磁碟。當然您也可以使用其它的 + RAID 模式。 + - Rebuilding ATA RAID1 Arrays + 重建(rebuild) ATA RAID1 陣列 - FreeBSD allows you to hot-replace a failed disk in an array. This requires - that you catch it before you reboot. + FreeBSD 允許您熱插拔磁碟陣列裡壞掉的磁碟， + 當然在重開機前就得先發現。 - You will probably see something like the following in /var/log/messages or in the &man.dmesg.8; - output: + 也許您會在 /var/log/messages(或 &man.dmesg.8; + 的輸出) 看到類似下面的訊息： ad6 on monster1 suffered a hard error. ad6: READ command timeout tag=0 serv=0 - resetting ad6: trying fallback to PIO mode ata3: resetting devices .. done ad6: hard error reading fsbn 1116119 of 0-7 (ad6 bn 1116119; cn 1107 tn 4 sn 11)\\ status=59 error=40 ar0: WARNING - mirror lost - Using &man.atacontrol.8;, check for further information: + 請用 &man.atacontrol.8; 來得到更多資訊： &prompt.root; atacontrol list ATA channel 0: Master: no device present Slave: acd0 <HL-DT-ST CD-ROM GCR-8520B/1.00> ATA/ATAPI rev 0 ATA channel 1: Master: no device present Slave: no device present ATA channel 2: Master: ad4 <MAXTOR 6L080J4/A93.0500> ATA/ATAPI rev 5 Slave: no device present ATA channel 3: Master: ad6 <MAXTOR 6L080J4/A93.0500> ATA/ATAPI rev 5 Slave: no device present &prompt.root; atacontrol status ar0 ar0: ATA RAID1 subdisks: ad4 ad6 status: DEGRADED - You will first need to detach the ata channel with the failed - disk so you can safely remove it: + 首先您得將損壞磁碟所在的 ata channel 卸載(detach)， + 如此才能安全地移除： &prompt.root; atacontrol detach ata3 - Replace the disk. + 用好的磁碟換下損壞的。 - Reattach the ata channel: + 重新載入(re-attach) ata channel： &prompt.root; atacontrol attach ata3 Master: ad6 <MAXTOR 6L080J4/A93.0500> ATA/ATAPI rev 5 Slave: no device present - Add the new disk to the array as a spare: + 將新的磁碟加入原本的磁碟陣列成為備援(spare) 磁碟： &prompt.root; atacontrol addspare ar0 ad6 - Rebuild the array: + 重建磁碟陣列： &prompt.root; atacontrol rebuild ar0 - It is possible to check on the progress by issuing the - following command: + 可以用下面指定來確認重建的進度： &prompt.root; dmesg | tail -10 [output removed] ad6: removed from configuration ad6: deleted from ar0 disk1 ad6: inserted into ar0 disk1 as spare &prompt.root; atacontrol status ar0 ar0: ATA RAID1 subdisks: ad4 ad6 status: REBUILDING 0% completed - Wait until this operation completes. + 等重建完就完成了。 Marc Fonvieille Contributed by - USB Storage Devices + USB 儲存裝置 USB disks - A lot of external storage solutions, nowadays, use the - Universal Serial Bus (USB): hard drives, USB thumbdrives, CD-R - burners, etc. &os; provides support for these devices. + 在現在，有許多外部儲存裝置採用 USB(Universal Serial Bus) 介面， + 例如硬碟、USB 拇指碟、CD-R 燒錄機等。 &os; 提供對這些裝置的支援。 - Configuration + 設定 - The USB mass storage devices driver, &man.umass.4;, - provides the support for USB storage devices. If you use the - GENERIC kernel, you do not have to change - anything in your configuration. If you use a custom kernel, - be sure that the following lines are present in your kernel - configuration file: + USB mass 儲存裝置驅動程式(&man.umass.4;)提供 USB 儲存裝置的支援。 + 但如果是用 GENERIC kernel，就不需要做任何設定變動 + 。 若是自訂 kernel，請確認 kernel 設定檔含有下面這幾行： device scbus device da device pass device uhci device ohci device usb device umass - The &man.umass.4; driver uses the SCSI subsystem to access - to the USB storage devices, your USB device will be seen as a - SCSI device by the system. Depending on the USB chipset on - your motherboard, you only need either device - uhci or device ohci, however - having both in the kernel configuration file is harmless. Do - not forget to compile and install the new kernel if you added - any lines. + &man.umass.4; 驅動程式透過 SCSI 子系統存取 USB 儲存裝置， + 您的 USB 裝置會被系統辨識成 SCSI 裝置。 依照您主機板上 USB 晶片型號， + 您只需要 device uhci 或 + device ohci 其中一個。 + 然而，將兩者都編進 kernel 也無妨。 只要別忘了在修改 kernel + 設定後重新編譯及安裝新的 kernel 就行了。 - If your USB device is a CD-R or DVD burner, the SCSI CD-ROM - driver, &man.cd.4;, must be added to the kernel via the - line: + 如果您的 USB 裝置是 CD-R 或 DVD 燒錄機，則 SCSI 光碟機驅動程式 + &man.cd.4; 必須寫入 kernel 設定檔，像這樣： device cd - Since the burner is seen as a SCSI drive, the driver - &man.atapicam.4; should not be used in the kernel - configuration. + 因為燒錄機會被當成 SCSI 裝置，所以 &man.atapicam.4; + 驅動程式不需要編入 kernel。 - Support for USB 2.0 controllers is provided on - &os;; however, you must add: + USB 2.0 控制器的支援由 &os;; 提供，然而必須在 kernel + 設定檔增加下面這行以提供 USB 2.0 支援： device ehci - to your configuration file for USB 2.0 support. Note - &man.uhci.4; and &man.ohci.4; drivers are still needed if you - want USB 1.X support. + 注意，如果您需要 USB 1.x 支援，您仍然需要將 &man.uhci.4; 及 + &man.ohci.4; 驅動程式編入 kernel。 - Testing the Configuration + 測試設定 The configuration is ready to be tested: plug in your USB device, and in the system message buffer (&man.dmesg.8;), the drive should appear as something like: umass0: USB Solid state disk, rev 1.10/1.00, addr 2 GEOM: create disk da0 dp=0xc2d74850 da0 at umass-sim0 bus 0 target 0 lun 0 da0: <Generic Traveling Disk 1.11> Removable Direct Access SCSI-2 device da0: 1.000MB/s transfers da0: 126MB (258048 512 byte sectors: 64H 32S/T 126C) Of course, the brand, the device node (da0) and other details can differ according to your configuration. Since the USB device is seen as a SCSI one, the camcontrol command can be used to list the USB storage devices attached to the system: &prompt.root; camcontrol devlist <Generic Traveling Disk 1.11> at scbus0 target 0 lun 0 (da0,pass0) If the drive comes with a file system, you should be able to mount it. The will help you to format and create partitions on the USB drive if needed. If you unplug the device (the disk must be unmounted before), you should see, in the system message buffer, something like the following: umass0: at uhub0 port 1 (addr 2) disconnected (da0:umass-sim0:0:0:0): lost device (da0:umass-sim0:0:0:0): removing device entry GEOM: destroy disk da0 dp=0xc2d74850 umass0: detached Further Reading Beside the Adding Disks and Mounting and Unmounting File Systems sections, reading various manual pages may be also useful: &man.umass.4;, &man.camcontrol.8;, and &man.usbdevs.8;. Mike Meyer Contributed by Creating and Using Optical Media (CDs) CDROMs creating Introduction CDs have a number of features that differentiate them from conventional disks. Initially, they were not writable by the user. They are designed so that they can be read continuously without delays to move the head between tracks. They are also much easier to transport between systems than similarly sized media were at the time. CDs do have tracks, but this refers to a section of data to be read continuously and not a physical property of the disk. To produce a CD on FreeBSD, you prepare the data files that are going to make up the tracks on the CD, then write the tracks to the CD. ISO 9660 file systems ISO 9660 The ISO 9660 file system was designed to deal with these differences. It unfortunately codifies file system limits that were common then. Fortunately, it provides an extension mechanism that allows properly written CDs to exceed those limits while still working with systems that do not support those extensions. sysutils/cdrtools The sysutils/cdrtools port includes &man.mkisofs.8;, a program that you can use to produce a data file containing an ISO 9660 file system. It has options that support various extensions, and is described below. CD burner ATAPI Which tool to use to burn the CD depends on whether your CD burner is ATAPI or something else. ATAPI CD burners use the burncd program that is part of the base system. SCSI and USB CD burners should use cdrecord from the sysutils/cdrtools port. burncd has a limited number of supported drives. To find out if a drive is supported, see the CD-R/RW supported drives list. CD burner ATAPI/CAM driver If you run &os; 5.X, &os; 4.8-RELEASE version or higher, it will be possible to use cdrecord and other tools for SCSI drives on an ATAPI hardware with the ATAPI/CAM module. If you want a CD burning software with a graphical user interface, you should have a look to X-CD-Roast or K3b. These tools are available as packages or from the sysutils/xcdroast and sysutils/k3b ports. X-CD-Roast and K3b require the ATAPI/CAM module with ATAPI hardware. mkisofs The &man.mkisofs.8; program, which is part of the sysutils/cdrtools port, produces an ISO 9660 file system that is an image of a directory tree in the &unix; file system name space. The simplest usage is: &prompt.root; mkisofs -o imagefile.iso /path/to/tree file systems ISO 9660 This command will create an imagefile.iso containing an ISO 9660 file system that is a copy of the tree at /path/to/tree. In the process, it will map the file names to names that fit the limitations of the standard ISO 9660 file system, and will exclude files that have names uncharacteristic of ISO file systems. file systems HFS file systems Joliet A number of options are available to overcome those restrictions. In particular, enables the Rock Ridge extensions common to &unix; systems, enables Joliet extensions used by Microsoft systems, and can be used to create HFS file systems used by &macos;. For CDs that are going to be used only on FreeBSD systems, can be used to disable all filename restrictions. When used with , it produces a file system image that is identical to the FreeBSD tree you started from, though it may violate the ISO 9660 standard in a number of ways. CDROMs creating bootable The last option of general use is . This is used to specify the location of the boot image for use in producing an El Torito bootable CD. This option takes an argument which is the path to a boot image from the top of the tree being written to the CD. By default, &man.mkisofs.8; creates an ISO image in the so-called floppy disk emulation mode, and thus expects the boot image to be exactly 1200, 1440 or 2880 KB in size. Some boot loaders, like the one used by the FreeBSD distribution disks, do not use emulation mode; in this case, the option should be used. So, if /tmp/myboot holds a bootable FreeBSD system with the boot image in /tmp/myboot/boot/cdboot, you could produce the image of an ISO 9660 file system in /tmp/bootable.iso like so: &prompt.root; mkisofs -R -no-emul-boot -b boot/cdboot -o /tmp/bootable.iso /tmp/myboot Having done that, if you have md configured in your kernel, you can mount the file system with: &prompt.root; mdconfig -a -t vnode -f /tmp/bootable.iso -u 0 &prompt.root; mount -t cd9660 /dev/md0 /mnt At which point you can verify that /mnt and /tmp/myboot are identical. There are many other options you can use with &man.mkisofs.8; to fine-tune its behavior. In particular: modifications to an ISO 9660 layout and the creation of Joliet and HFS discs. See the &man.mkisofs.8; manual page for details. burncd CDROMs burning If you have an ATAPI CD burner, you can use the burncd command to burn an ISO image onto a CD. burncd is part of the base system, installed as /usr/sbin/burncd. Usage is very simple, as it has few options: &prompt.root; burncd -f cddevice data imagefile.iso fixate Will burn a copy of imagefile.iso on cddevice. The default device is /dev/acd0. See &man.burncd.8; for options to set the write speed, eject the CD after burning, and write audio data. cdrecord If you do not have an ATAPI CD burner, you will have to use cdrecord to burn your CDs. cdrecord is not part of the base system; you must install it from either the port at sysutils/cdrtools or the appropriate package. Changes to the base system can cause binary versions of this program to fail, possibly resulting in a coaster. You should therefore either upgrade the port when you upgrade your system, or if you are tracking -STABLE, upgrade the port when a new version becomes available. While cdrecord has many options, basic usage is even simpler than burncd. Burning an ISO 9660 image is done with: &prompt.root; cdrecord dev=device imagefile.iso The tricky part of using cdrecord is finding the to use. To find the proper setting, use the flag of cdrecord, which might produce results like this: CDROMs burning &prompt.root; cdrecord -scanbus Cdrecord-Clone 2.01 (i386-unknown-freebsd7.0) Copyright (C) 1995-2004 Jörg Schilling Using libscg version 'schily-0.1' scsibus0: 0,0,0 0) 'SEAGATE ' 'ST39236LW ' '0004' Disk 0,1,0 1) 'SEAGATE ' 'ST39173W ' '5958' Disk 0,2,0 2) * 0,3,0 3) 'iomega ' 'jaz 1GB ' 'J.86' Removable Disk 0,4,0 4) 'NEC ' 'CD-ROM DRIVE:466' '1.26' Removable CD-ROM 0,5,0 5) * 0,6,0 6) * 0,7,0 7) * scsibus1: 1,0,0 100) * 1,1,0 101) * 1,2,0 102) * 1,3,0 103) * 1,4,0 104) * 1,5,0 105) 'YAMAHA ' 'CRW4260 ' '1.0q' Removable CD-ROM 1,6,0 106) 'ARTEC ' 'AM12S ' '1.06' Scanner 1,7,0 107) * This lists the appropriate value for the devices on the list. Locate your CD burner, and use the three numbers separated by commas as the value for . In this case, the CRW device is 1,5,0, so the appropriate input would be . There are easier ways to specify this value; see &man.cdrecord.1; for details. That is also the place to look for information on writing audio tracks, controlling the speed, and other things. Duplicating Audio CDs You can duplicate an audio CD by extracting the audio data from the CD to a series of files, and then writing these files to a blank CD. The process is slightly different for ATAPI and SCSI drives. SCSI Drives Use cdda2wav to extract the audio. &prompt.user; cdda2wav -v255 -D2,0 -B -Owav Use cdrecord to write the .wav files. &prompt.user; cdrecord -v dev=2,0 -dao -useinfo *.wav Make sure that 2,0 is set appropriately, as described in . ATAPI Drives The ATAPI CD driver makes each track available as /dev/acddtnn, where d is the drive number, and nn is the track number written with two decimal digits, prefixed with zero as needed. So the first track on the first disk is /dev/acd0t01, the second is /dev/acd0t02, the third is /dev/acd0t03, and so on. Make sure the appropriate files exist in /dev. If the entries are missing, force the system to retaste the media: &prompt.root; dd if=/dev/acd0 of=/dev/null count=1 Extract each track using &man.dd.1;. You must also use a specific block size when extracting the files. &prompt.root; dd if=/dev/acd0t01 of=track1.cdr bs=2352 &prompt.root; dd if=/dev/acd0t02 of=track2.cdr bs=2352 ... Burn the extracted files to disk using burncd. You must specify that these are audio files, and that burncd should fixate the disk when finished. &prompt.root; burncd -f /dev/acd0 audio track1.cdr track2.cdr ... fixate Duplicating Data CDs You can copy a data CD to a image file that is functionally equivalent to the image file created with &man.mkisofs.8;, and you can use it to duplicate any data CD. The example given here assumes that your CDROM device is acd0. Substitute your correct CDROM device. &prompt.root; dd if=/dev/acd0 of=file.iso bs=2048 Now that you have an image, you can burn it to CD as described above. Using Data CDs Now that you have created a standard data CDROM, you probably want to mount it and read the data on it. By default, &man.mount.8; assumes that a file system is of type ufs. If you try something like: &prompt.root; mount /dev/cd0 /mnt you will get a complaint about Incorrect super block, and no mount. The CDROM is not a UFS file system, so attempts to mount it as such will fail. You just need to tell &man.mount.8; that the file system is of type ISO9660, and everything will work. You do this by specifying the option &man.mount.8;. For example, if you want to mount the CDROM device, /dev/cd0, under /mnt, you would execute: &prompt.root; mount -t cd9660 /dev/cd0 /mnt Note that your device name (/dev/cd0 in this example) could be different, depending on the interface your CDROM uses. Also, the option just executes &man.mount.cd9660.8;. The above example could be shortened to: &prompt.root; mount_cd9660 /dev/cd0 /mnt You can generally use data CDROMs from any vendor in this way. Disks with certain ISO 9660 extensions might behave oddly, however. For example, Joliet disks store all filenames in two-byte Unicode characters. The FreeBSD kernel does not speak Unicode (yet!), so non-English characters show up as question marks. (The FreeBSD CD9660 driver includes hooks to load an appropriate Unicode conversion table on the fly. Modules for some of the common encodings are available via the sysutils/cd9660_unicode port.) Occasionally, you might get Device not configured when trying to mount a CDROM. This usually means that the CDROM drive thinks that there is no disk in the tray, or that the drive is not visible on the bus. It can take a couple of seconds for a CDROM drive to realize that it has been fed, so be patient. Sometimes, a SCSI CDROM may be missed because it did not have enough time to answer the bus reset. If you have a SCSI CDROM please add the following option to your kernel configuration and rebuild your kernel. options SCSI_DELAY=15000 This tells your SCSI bus to pause 15 seconds during boot, to give your CDROM drive every possible chance to answer the bus reset. Burning Raw Data CDs You can choose to burn a file directly to CD, without creating an ISO 9660 file system. Some people do this for backup purposes. This runs more quickly than burning a standard CD: &prompt.root; burncd -f /dev/acd1 -s 12 data archive.tar.gz fixate In order to retrieve the data burned to such a CD, you must read data from the raw device node: &prompt.root; tar xzvf /dev/acd1 You cannot mount this disk as you would a normal CDROM. Such a CDROM cannot be read under any operating system except FreeBSD. If you want to be able to mount the CD, or share data with another operating system, you must use &man.mkisofs.8; as described above. Marc Fonvieille Contributed by CD burner ATAPI/CAM driver Using the ATAPI/CAM Driver This driver allows ATAPI devices (CD-ROM, CD-RW, DVD drives etc...) to be accessed through the SCSI subsystem, and so allows the use of applications like sysutils/cdrdao or &man.cdrecord.1;. To use this driver, you will need to add the following line to your kernel configuration file: device atapicam You also need the following lines in your kernel configuration file: device ata device scbus device cd device pass which should already be present. Then rebuild, install your new kernel, and reboot your machine. During the boot process, your burner should show up, like so: acd0: CD-RW <MATSHITA CD-RW/DVD-ROM UJDA740> at ata1-master PIO4 cd0 at ata1 bus 0 target 0 lun 0 cd0: <MATSHITA CDRW/DVD UJDA740 1.00> Removable CD-ROM SCSI-0 device cd0: 16.000MB/s transfers cd0: Attempt to query device size failed: NOT READY, Medium not present - tray closed The drive could now be accessed via the /dev/cd0 device name, for example to mount a CD-ROM on /mnt, just type the following: &prompt.root; mount -t cd9660 /dev/cd0 /mnt As root, you can run the following command to get the SCSI address of the burner: &prompt.root; camcontrol devlist <MATSHITA CDRW/DVD UJDA740 1.00> at scbus1 target 0 lun 0 (pass0,cd0) So 1,0,0 will be the SCSI address to use with &man.cdrecord.1; and other SCSI application. For more information about ATAPI/CAM and SCSI system, refer to the &man.atapicam.4; and &man.cam.4; manual pages. Marc Fonvieille Contributed by Andy Polyakov With inputs from Creating and Using Optical Media (DVDs) DVD burning Introduction Compared to the CD, the DVD is the next generation of optical media storage technology. The DVD can hold more data than any CD and is nowadays the standard for video publishing. Five physical recordable formats can be defined for what we will call a recordable DVD: DVD-R: This was the first DVD recordable format available. The DVD-R standard is defined by the DVD Forum. This format is write once. DVD-RW: This is the rewriteable version of the DVD-R standard. A DVD-RW can be rewritten about 1000 times. DVD-RAM: This is also a rewriteable format supported by the DVD Forum. A DVD-RAM can be seen as a removable hard drive. However, this media is not compatible with most DVD-ROM drives and DVD-Video players; only a few DVD writers support the DVD-RAM format. DVD+RW: This is a rewriteable format defined by the DVD+RW Alliance. A DVD+RW can be rewritten about 1000 times. DVD+R: This format is the write once variation of the DVD+RW format. A single layer recordable DVD can hold up to 4,700,000,000 bytes which is actually 4.38 GB or 4485 MB (1 kilobyte is 1024 bytes). A distinction must be made between the physical media and the application. For example, a DVD-Video is a specific file layout that can be written on any recordable DVD physical media: DVD-R, DVD+R, DVD-RW etc. Before choosing the type of media, you must be sure that both the burner and the DVD-Video player (a standalone player or a DVD-ROM drive on a computer) are compatible with the media under consideration. Configuration The program &man.growisofs.1; will be used to perform DVD recording. This command is part of the dvd+rw-tools utilities (sysutils/dvd+rw-tools). The dvd+rw-tools support all DVD media types. These tools use the SCSI subsystem to access to the devices, therefore the ATAPI/CAM support must be added to your kernel. If your burner uses the USB interface this addition is useless, and you should read the for more details on USB devices configuration. You also have to enable DMA access for ATAPI devices, this can be done in adding the following line to the /boot/loader.conf file: hw.ata.atapi_dma="1" Before attempting to use the dvd+rw-tools you should consult the dvd+rw-tools' hardware compatibility notes for any information related to your DVD burner. If you want a graphical user interface, you should have a look to K3b (sysutils/k3b) which provides a user friendly interface to &man.growisofs.1; and many others burning tools. Burning Data DVDs The &man.growisofs.1; command is a frontend to mkisofs, it will invoke &man.mkisofs.8; to create the file system layout and will perform the write on the DVD. This means you do not need to create an image of the data before the burning process. To burn onto a DVD+R or a DVD-R the data from the /path/to/data directory, use the following command: &prompt.root; growisofs -dvd-compat -Z /dev/cd0 -J -R /path/to/data The options are passed to &man.mkisofs.8; for the file system creation (in this case: an ISO 9660 file system with Joliet and Rock Ridge extensions), consult the &man.mkisofs.8; manual page for more details. The option is used for the initial session recording in any case: multiple sessions or not. The DVD device, /dev/cd0, must be changed according to your configuration. The parameter will close the disk, the recording will be unappendable. In return this should provide better media compatibility with DVD-ROM drives. It is also possible to burn a pre-mastered image, for example to burn the image imagefile.iso, we will run: &prompt.root; growisofs -dvd-compat -Z /dev/cd0=imagefile.iso The write speed should be detected and automatically set according to the media and the drive being used. If you want to force the write speed, use the parameter. For more information, read the &man.growisofs.1; manual page. DVD DVD-Video Burning a DVD-Video A DVD-Video is a specific file layout based on ISO 9660 and the micro-UDF (M-UDF) specifications. The DVD-Video also presents a specific data structure hierarchy, it is the reason why you need a particular program such as multimedia/dvdauthor to author the DVD. If you already have an image of the DVD-Video file system, just burn it in the same way as for any image, see the previous section for an example. If you have made the DVD authoring and the result is in, for example, the directory /path/to/video, the following command should be used to burn the DVD-Video: &prompt.root; growisofs -Z /dev/cd0 -dvd-video /path/to/video The option will be passed down to &man.mkisofs.8; and will instruct it to create a DVD-Video file system layout. Beside this, the option implies &man.growisofs.1; option. DVD DVD+RW Using a DVD+RW Unlike CD-RW, a virgin DVD+RW needs to be formatted before first use. The &man.growisofs.1; program will take care of it automatically whenever appropriate, which is the recommended way. However you can use the dvd+rw-format command to format the DVD+RW: &prompt.root; dvd+rw-format /dev/cd0 You need to perform this operation just once, keep in mind that only virgin DVD+RW medias need to be formatted. Then you can burn the DVD+RW in the way seen in previous sections. If you want to burn new data (burn a totally new file system not append some data) onto a DVD+RW, you do not need to blank it, you just have to write over the previous recording (in performing a new initial session), like this: &prompt.root; growisofs -Z /dev/cd0 -J -R /path/to/newdata DVD+RW format offers the possibility to easily append data to a previous recording. The operation consists in merging a new session to the existing one, it is not multisession writing, &man.growisofs.1; will grow the ISO 9660 file system present on the media. For example, if we want to append data to our previous DVD+RW, we have to use the following: &prompt.root; growisofs -M /dev/cd0 -J -R /path/to/nextdata The same &man.mkisofs.8; options we used to burn the initial session should be used during next writes. You may want to use the option if you want better media compatibility with DVD-ROM drives. In the DVD+RW case, this will not prevent you from adding data. If for any reason you really want to blank the media, do the following: &prompt.root; growisofs -Z /dev/cd0=/dev/zero DVD DVD-RW Using a DVD-RW A DVD-RW accepts two disc formats: the incremental sequential one and the restricted overwrite. By default DVD-RW discs are in sequential format. A virgin DVD-RW can be directly written without the need of a formatting operation, however a non-virgin DVD-RW in sequential format needs to be blanked before to be able to write a new initial session. To blank a DVD-RW in sequential mode, run: &prompt.root; dvd+rw-format -blank=full /dev/cd0 A full blanking () will take about one hour on a 1x media. A fast blanking can be performed using the option if the DVD-RW will be recorded in Disk-At-Once (DAO) mode. To burn the DVD-RW in DAO mode, use the command: &prompt.root; growisofs -use-the-force-luke=dao -Z /dev/cd0=imagefile.iso The option should not be required since &man.growisofs.1; attempts to detect minimally (fast blanked) media and engage DAO write. In fact one should use restricted overwrite mode with any DVD-RW, this format is more flexible than the default incremental sequential one. To write data on a sequential DVD-RW, use the same instructions as for the other DVD formats: &prompt.root; growisofs -Z /dev/cd0 -J -R /path/to/data If you want to append some data to your previous recording, you will have to use the &man.growisofs.1; option. However, if you perform data addition on a DVD-RW in incremental sequential mode, a new session will be created on the disc and the result will be a multi-session disc. A DVD-RW in restricted overwrite format does not need to be blanked before a new initial session, you just have to overwrite the disc with the option, this is similar to the DVD+RW case. It is also possible to grow an existing ISO 9660 file system written on the disc in a same way as for a DVD+RW with the option. The result will be a one-session DVD. To put a DVD-RW in the restricted overwrite format, the following command must be used: &prompt.root; dvd+rw-format /dev/cd0 To change back to the sequential format use: &prompt.root; dvd+rw-format -blank=full /dev/cd0 Multisession Very few DVD-ROM drives support multisession DVDs, they will most of time, hopefully, only read the first session. DVD+R, DVD-R and DVD-RW in sequential format can accept multiple sessions, the notion of multiple sessions does not exist for the DVD+RW and the DVD-RW restricted overwrite formats. Using the following command after an initial (non-closed) session on a DVD+R, DVD-R, or DVD-RW in sequential format, will add a new session to the disc: &prompt.root; growisofs -M /dev/cd0 -J -R /path/to/nextdata Using this command line with a DVD+RW or a DVD-RW in restricted overwrite mode, will append data in merging the new session to the existing one. The result will be a single-session disc. This is the way used to add data after an initial write on these medias. Some space on the media is used between each session for end and start of sessions. Therefore, one should add sessions with large amount of data to optimize media space. The number of sessions is limited to 154 for a DVD+R, about 2000 for a DVD-R, and 127 for a DVD+R Double Layer. For More Information To obtain more information about a DVD, the dvd+rw-mediainfo /dev/cd0 command can be ran with the disc in the drive. More information about the dvd+rw-tools can be found in the &man.growisofs.1; manual page, on the dvd+rw-tools web site and in the cdwrite mailing list archives. The dvd+rw-mediainfo output of the resulting recording or the media with issues is mandatory for any problem report. Without this output, it will be quite impossible to help you. Julio Merino Original work by Martin Karlsson Rewritten by Creating and Using Floppy Disks Storing data on floppy disks is sometimes useful, for example when one does not have any other removable storage media or when one needs to transfer small amounts of data to another computer. This section will explain how to use floppy disks in FreeBSD. It will primarily cover formatting and usage of 3.5inch DOS floppies, but the concepts are similar for other floppy disk formats. Formatting Floppies The Device Floppy disks are accessed through entries in /dev, just like other devices. To access the raw floppy disk, simply use /dev/fdN. Formatting A floppy disk needs to be low-level formated before it can be used. This is usually done by the vendor, but formatting is a good way to check media integrity. Although it is possible to force larger (or smaller) disk sizes, 1440kB is what most floppy disks are designed for. To low-level format the floppy disk you need to use &man.fdformat.1;. This utility expects the device name as an argument. Make note of any error messages, as these can help determine if the disk is good or bad. Formatting Floppy Disks Use the /dev/fdN devices to format the floppy. Insert a new 3.5inch floppy disk in your drive and issue: &prompt.root; /usr/sbin/fdformat -f 1440 /dev/fd0 The Disk Label After low-level formatting the disk, you will need to place a disk label on it. This disk label will be destroyed later, but it is needed by the system to determine the size of the disk and its geometry later. The new disk label will take over the whole disk, and will contain all the proper information about the geometry of the floppy. The geometry values for the disk label are listed in /etc/disktab. You can run now &man.bsdlabel.8; like so: &prompt.root; /sbin/bsdlabel -B -r -w /dev/fd0 fd1440 Since &os; 5.1-RELEASE, the &man.bsdlabel.8; utility replaces the old &man.bsdlabel.8; program. With &man.bsdlabel.8; a number of obsolete options and parameters have been retired; in the example above the option should be removed. For more information, please refer to the &man.bsdlabel.8; manual page. The File System Now the floppy is ready to be high-level formated. This will place a new file system on it, which will let FreeBSD read and write to the disk. After creating the new file system, the disk label is destroyed, so if you want to reformat the disk, you will have to recreate the disk label. The floppy's file system can be either UFS or FAT. FAT is generally a better choice for floppies. To put a new file system on the floppy, issue: &prompt.root; /sbin/newfs_msdos /dev/fd0 The disk is now ready for use. Using the Floppy To use the floppy, mount it with &man.mount.msdos.8;. One can also use emulators/mtools from the ports collection. Creating and Using Data Tapes tape media The major tape media are the 4mm, 8mm, QIC, mini-cartridge and DLT. 4mm (DDS: Digital Data Storage) tape media DDS (4mm) tapes tape media QIC tapes 4mm tapes are replacing QIC as the workstation backup media of choice. This trend accelerated greatly when Conner purchased Archive, a leading manufacturer of QIC drives, and then stopped production of QIC drives. 4mm drives are small and quiet but do not have the reputation for reliability that is enjoyed by 8mm drives. The cartridges are less expensive and smaller (3 x 2 x 0.5 inches, 76 x 51 x 12 mm) than 8mm cartridges. 4mm, like 8mm, has comparatively short head life for the same reason, both use helical scan. Data throughput on these drives starts ~150 kB/s, peaking at ~500 kB/s. Data capacity starts at 1.3 GB and ends at 2.0 GB. Hardware compression, available with most of these drives, approximately doubles the capacity. Multi-drive tape library units can have 6 drives in a single cabinet with automatic tape changing. Library capacities reach 240 GB. The DDS-3 standard now supports tape capacities up to 12 GB (or 24 GB compressed). 4mm drives, like 8mm drives, use helical-scan. All the benefits and drawbacks of helical-scan apply to both 4mm and 8mm drives. Tapes should be retired from use after 2,000 passes or 100 full backups. 8mm (Exabyte) tape media Exabyte (8mm) tapes 8mm tapes are the most common SCSI tape drives; they are the best choice of exchanging tapes. Nearly every site has an Exabyte 2 GB 8mm tape drive. 8mm drives are reliable, convenient and quiet. Cartridges are inexpensive and small (4.8 x 3.3 x 0.6 inches; 122 x 84 x 15 mm). One downside of 8mm tape is relatively short head and tape life due to the high rate of relative motion of the tape across the heads. Data throughput ranges from ~250 kB/s to ~500 kB/s. Data sizes start at 300 MB and go up to 7 GB. Hardware compression, available with most of these drives, approximately doubles the capacity. These drives are available as single units or multi-drive tape libraries with 6 drives and 120 tapes in a single cabinet. Tapes are changed automatically by the unit. Library capacities reach 840+ GB. The Exabyte Mammoth model supports 12 GB on one tape (24 GB with compression) and costs approximately twice as much as conventional tape drives. Data is recorded onto the tape using helical-scan, the heads are positioned at an angle to the media (approximately 6 degrees). The tape wraps around 270 degrees of the spool that holds the heads. The spool spins while the tape slides over the spool. The result is a high density of data and closely packed tracks that angle across the tape from one edge to the other. QIC tape media QIC-150 QIC-150 tapes and drives are, perhaps, the most common tape drive and media around. QIC tape drives are the least expensive serious backup drives. The downside is the cost of media. QIC tapes are expensive compared to 8mm or 4mm tapes, up to 5 times the price per GB data storage. But, if your needs can be satisfied with a half-dozen tapes, QIC may be the correct choice. QIC is the most common tape drive. Every site has a QIC drive of some density or another. Therein lies the rub, QIC has a large number of densities on physically similar (sometimes identical) tapes. QIC drives are not quiet. These drives audibly seek before they begin to record data and are clearly audible whenever reading, writing or seeking. QIC tapes measure (6 x 4 x 0.7 inches; 152 x 102 x 17 mm). Data throughput ranges from ~150 kB/s to ~500 kB/s. Data capacity ranges from 40 MB to 15 GB. Hardware compression is available on many of the newer QIC drives. QIC drives are less frequently installed; they are being supplanted by DAT drives. Data is recorded onto the tape in tracks. The tracks run along the long axis of the tape media from one end to the other. The number of tracks, and therefore the width of a track, varies with the tape's capacity. Most if not all newer drives provide backward-compatibility at least for reading (but often also for writing). QIC has a good reputation regarding the safety of the data (the mechanics are simpler and more robust than for helical scan drives). Tapes should be retired from use after 5,000 backups. DLT tape media DLT DLT has the fastest data transfer rate of all the drive types listed here. The 1/2" (12.5mm) tape is contained in a single spool cartridge (4 x 4 x 1 inches; 100 x 100 x 25 mm). The cartridge has a swinging gate along one entire side of the cartridge. The drive mechanism opens this gate to extract the tape leader. The tape leader has an oval hole in it which the drive uses to hook the tape. The take-up spool is located inside the tape drive. All the other tape cartridges listed here (9 track tapes are the only exception) have both the supply and take-up spools located inside the tape cartridge itself. Data throughput is approximately 1.5 MB/s, three times the throughput of 4mm, 8mm, or QIC tape drives. Data capacities range from 10 GB to 20 GB for a single drive. Drives are available in both multi-tape changers and multi-tape, multi-drive tape libraries containing from 5 to 900 tapes over 1 to 20 drives, providing from 50 GB to 9 TB of storage. With compression, DLT Type IV format supports up to 70 GB capacity. Data is recorded onto the tape in tracks parallel to the direction of travel (just like QIC tapes). Two tracks are written at once. Read/write head lifetimes are relatively long; once the tape stops moving, there is no relative motion between the heads and the tape. AIT tape media AIT AIT is a new format from Sony, and can hold up to 50 GB (with compression) per tape. The tapes contain memory chips which retain an index of the tape's contents. This index can be rapidly read by the tape drive to determine the position of files on the tape, instead of the several minutes that would be required for other tapes. Software such as SAMS:Alexandria can operate forty or more AIT tape libraries, communicating directly with the tape's memory chip to display the contents on screen, determine what files were backed up to which tape, locate the correct tape, load it, and restore the data from the tape. Libraries like this cost in the region of $20,000, pricing them a little out of the hobbyist market. Using a New Tape for the First Time The first time that you try to read or write a new, completely blank tape, the operation will fail. The console messages should be similar to: sa0(ncr1:4:0): NOT READY asc:4,1 sa0(ncr1:4:0): Logical unit is in process of becoming ready The tape does not contain an Identifier Block (block number 0). All QIC tape drives since the adoption of QIC-525 standard write an Identifier Block to the tape. There are two solutions: mt fsf 1 causes the tape drive to write an Identifier Block to the tape. Use the front panel button to eject the tape. Re-insert the tape and dump data to the tape. dump will report DUMP: End of tape detected and the console will show: HARDWARE FAILURE info:280 asc:80,96. rewind the tape using: mt rewind. Subsequent tape operations are successful. Backups to Floppies Can I Use Floppies for Backing Up My Data? backup floppies floppy disks Floppy disks are not really a suitable media for making backups as: The media is unreliable, especially over long periods of time. Backing up and restoring is very slow. They have a very limited capacity (the days of backing up an entire hard disk onto a dozen or so floppies has long since passed). However, if you have no other method of backing up your data then floppy disks are better than no backup at all. If you do have to use floppy disks then ensure that you use good quality ones. Floppies that have been lying around the office for a couple of years are a bad choice. Ideally use new ones from a reputable manufacturer. So How Do I Backup My Data to Floppies? The best way to backup to floppy disk is to use &man.tar.1; with the (multi volume) option, which allows backups to span multiple floppies. To backup all the files in the current directory and sub-directory use this (as root): &prompt.root; tar Mcvf /dev/fd0 * When the first floppy is full &man.tar.1; will prompt you to insert the next volume (because &man.tar.1; is media independent it refers to volumes; in this context it means floppy disk). Prepare volume #2 for /dev/fd0 and hit return: This is repeated (with the volume number incrementing) until all the specified files have been archived. Can I Compress My Backups? tar gzip compression Unfortunately, &man.tar.1; will not allow the option to be used for multi-volume archives. You could, of course, &man.gzip.1; all the files, &man.tar.1; them to the floppies, then &man.gunzip.1; the files again! How Do I Restore My Backups? To restore the entire archive use: &prompt.root; tar Mxvf /dev/fd0 There are two ways that you can use to restore only specific files. First, you can start with the first floppy and use: &prompt.root; tar Mxvf /dev/fd0 filename The utility &man.tar.1; will prompt you to insert subsequent floppies until it finds the required file. Alternatively, if you know which floppy the file is on then you can simply insert that floppy and use the same command as above. Note that if the first file on the floppy is a continuation from the previous one then &man.tar.1; will warn you that it cannot restore it, even if you have not asked it to! Lowell Gilbert Original work by Backup Strategies The first requirement in devising a backup plan is to make sure that all of the following problems are covered: Disk failure Accidental file deletion Random file corruption Complete machine destruction (e.g. fire), including destruction of any on-site backups. It is perfectly possible that some systems will be best served by having each of these problems covered by a completely different technique. Except for strictly personal systems with very low-value data, it is unlikely that one technique would cover all of them. Some of the techniques in the toolbox are: Archives of the whole system, backed up onto permanent media offsite. This actually provides protection against all of the possible problems listed above, but is slow and inconvenient to restore from. You can keep copies of the backups onsite and/or online, but there will still be inconveniences in restoring files, especially for non-privileged users. Filesystem snapshots. This is really only helpful in the accidental file deletion scenario, but it can be very helpful in that case, and is quick and easy to deal with. Copies of whole filesystems and/or disks (e.g. periodic rsync of the whole machine). This is generally most useful in networks with unique requirements. For general protection against disk failure, it is usually inferior to RAID. For restoring accidentally deleted files, it can be comparable to UFS snapshots, but that depends on your preferences. RAID. Minimizes or avoids downtime when a disk fails. At the expense of having to deal with disk failures more often (because you have more disks), albeit at a much lower urgency. Checking fingerprints of files. The &man.mtree.8; utility is very useful for this. Although it is not a backup technique, it helps guarantee that you will notice when you need to resort to your backups. This is particularly important for offline backups, and should be checked periodically. It is quite easy to come up with even more techniques, many of them variations on the ones listed above. Specialized requirements will usually lead to specialized techniques (for example, backing up a live database usually requires a method particular to the database software as an intermediate step). The important thing is to know what dangers you want to protect against, and how you will handle each. Backup Basics The three major backup programs are &man.dump.8;, &man.tar.1;, and &man.cpio.1;. Dump and Restore backup software dump / restore dump restore The traditional &unix; backup programs are dump and restore. They operate on the drive as a collection of disk blocks, below the abstractions of files, links and directories that are created by the file systems. dump backs up an entire file system on a device. It is unable to backup only part of a file system or a directory tree that spans more than one file system. dump does not write files and directories to tape, but rather writes the raw data blocks that comprise files and directories. If you use dump on your root directory, you would not back up /home, /usr or many other directories since these are typically mount points for other file systems or symbolic links into those file systems. dump has quirks that remain from its early days in Version 6 of AT&T UNIX (circa 1975). The default parameters are suitable for 9-track tapes (6250 bpi), not the high-density media available today (up to 62,182 ftpi). These defaults must be overridden on the command line to utilize the capacity of current tape drives. .rhosts It is also possible to backup data across the network to a tape drive attached to another computer with rdump and rrestore. Both programs rely upon &man.rcmd.3; and &man.ruserok.3; to access the remote tape drive. Therefore, the user performing the backup must be listed in the .rhosts file on the remote computer. The arguments to rdump and rrestore must be suitable to use on the remote computer. When rdumping from a FreeBSD computer to an Exabyte tape drive connected to a Sun called komodo, use: &prompt.root; /sbin/rdump 0dsbfu 54000 13000 126 komodo:/dev/nsa8 /dev/da0a 2>&1 Beware: there are security implications to allowing .rhosts authentication. Evaluate your situation carefully. It is also possible to use dump and restore in a more secure fashion over ssh. Using <command>dump</command> over <application>ssh</application> &prompt.root; /sbin/dump -0uan -f - /usr | gzip -2 | ssh -c blowfish \ targetuser@targetmachine.example.com dd of=/mybigfiles/dump-usr-l0.gz Or using dump's built-in method, setting the environment variable RSH: Using <command>dump</command> over <application>ssh</application> with <envar>RSH</envar> set &prompt.root; RSH=/usr/bin/ssh /sbin/dump -0uan -f targetuser@targetmachine.example.com:/dev/sa0 /usr <command>tar</command> backup software tar &man.tar.1; also dates back to Version 6 of AT&T UNIX (circa 1975). tar operates in cooperation with the file system; it writes files and directories to tape. tar does not support the full range of options that are available from &man.cpio.1;, but it does not require the unusual command pipeline that cpio uses. tar On FreeBSD 5.3 and later, both GNU tar and the default bsdtar are available. The GNU version can be invoked with gtar. It supports remote devices using the same syntax as rdump. To tar to an Exabyte tape drive connected to a Sun called komodo, use: &prompt.root; /usr/bin/gtar cf komodo:/dev/nsa8 . 2>&1 The same could be accomplished with bsdtar by using a pipeline and rsh to send the data to a remote tape drive. &prompt.root; tar cf - . | rsh hostname dd of=tape-device obs=20b If you are worried about the security of backing up over a network you should use the ssh command instead of rsh. <command>cpio</command> backup software cpio &man.cpio.1; is the original &unix; file interchange tape program for magnetic media. cpio has options (among many others) to perform byte-swapping, write a number of different archive formats, and pipe the data to other programs. This last feature makes cpio an excellent choice for installation media. cpio does not know how to walk the directory tree and a list of files must be provided through stdin. cpio cpio does not support backups across the network. You can use a pipeline and rsh to send the data to a remote tape drive. &prompt.root; for f in directory_list; do find $f >> backup.list done &prompt.root; cpio -v -o --format=newc < backup.list | ssh user@host "cat > backup_device" Where directory_list is the list of directories you want to back up, user@host is the user/hostname combination that will be performing the backups, and backup_device is where the backups should be written to (e.g., /dev/nsa0). <command>pax</command> backup software pax pax POSIX IEEE &man.pax.1; is IEEE/&posix;'s answer to tar and cpio. Over the years the various versions of tar and cpio have gotten slightly incompatible. So rather than fight it out to fully standardize them, &posix; created a new archive utility. pax attempts to read and write many of the various cpio and tar formats, plus new formats of its own. Its command set more resembles cpio than tar. <application>Amanda</application> backup software Amanda Amanda Amanda (Advanced Maryland Network Disk Archiver) is a client/server backup system, rather than a single program. An Amanda server will backup to a single tape drive any number of computers that have Amanda clients and a network connection to the Amanda server. A common problem at sites with a number of large disks is that the length of time required to backup to data directly to tape exceeds the amount of time available for the task. Amanda solves this problem. Amanda can use a holding disk to backup several file systems at the same time. Amanda creates archive sets: a group of tapes used over a period of time to create full backups of all the file systems listed in Amanda's configuration file. The archive set also contains nightly incremental (or differential) backups of all the file systems. Restoring a damaged file system requires the most recent full backup and the incremental backups. The configuration file provides fine control of backups and the network traffic that Amanda generates. Amanda will use any of the above backup programs to write the data to tape. Amanda is available as either a port or a package, it is not installed by default. Do Nothing Do nothing is not a computer program, but it is the most widely used backup strategy. There are no initial costs. There is no backup schedule to follow. Just say no. If something happens to your data, grin and bear it! If your time and your data is worth little to nothing, then Do nothing is the most suitable backup program for your computer. But beware, &unix; is a useful tool, you may find that within six months you have a collection of files that are valuable to you. Do nothing is the correct backup method for /usr/obj and other directory trees that can be exactly recreated by your computer. An example is the files that comprise the HTML or &postscript; version of this Handbook. These document formats have been created from SGML input files. Creating backups of the HTML or &postscript; files is not necessary. The SGML files are backed up regularly. Which Backup Program Is Best? LISA &man.dump.8; Period. Elizabeth D. Zwicky torture tested all the backup programs discussed here. The clear choice for preserving all your data and all the peculiarities of &unix; file systems is dump. Elizabeth created file systems containing a large variety of unusual conditions (and some not so unusual ones) and tested each program by doing a backup and restore of those file systems. The peculiarities included: files with holes, files with holes and a block of nulls, files with funny characters in their names, unreadable and unwritable files, devices, files that change size during the backup, files that are created/deleted during the backup and more. She presented the results at LISA V in Oct. 1991. See torture-testing Backup and Archive Programs. Emergency Restore Procedure Before the Disaster There are only four steps that you need to perform in preparation for any disaster that may occur. bsdlabel First, print the bsdlabel from each of your disks (e.g. bsdlabel da0 | lpr), your file system table (/etc/fstab) and all boot messages, two copies of each. fix-it floppies Second, determine that the boot and fix-it floppies (boot.flp and fixit.flp) have all your devices. The easiest way to check is to reboot your machine with the boot floppy in the floppy drive and check the boot messages. If all your devices are listed and functional, skip on to step three. Otherwise, you have to create two custom bootable floppies which have a kernel that can mount all of your disks and access your tape drive. These floppies must contain: fdisk, bsdlabel, newfs, mount, and whichever backup program you use. These programs must be statically linked. If you use dump, the floppy must contain restore. Third, create backup tapes regularly. Any changes that you make after your last backup may be irretrievably lost. Write-protect the backup tapes. Fourth, test the floppies (either boot.flp and fixit.flp or the two custom bootable floppies you made in step two.) and backup tapes. Make notes of the procedure. Store these notes with the bootable floppy, the printouts and the backup tapes. You will be so distraught when restoring that the notes may prevent you from destroying your backup tapes (How? In place of tar xvf /dev/sa0, you might accidentally type tar cvf /dev/sa0 and over-write your backup tape). For an added measure of security, make bootable floppies and two backup tapes each time. Store one of each at a remote location. A remote location is NOT the basement of the same office building. A number of firms in the World Trade Center learned this lesson the hard way. A remote location should be physically separated from your computers and disk drives by a significant distance. A Script for Creating a Bootable Floppy After the Disaster The key question is: did your hardware survive? You have been doing regular backups so there is no need to worry about the software. If the hardware has been damaged, the parts should be replaced before attempting to use the computer. If your hardware is okay, check your floppies. If you are using a custom boot floppy, boot single-user (type -s at the boot: prompt). Skip the following paragraph. If you are using the boot.flp and fixit.flp floppies, keep reading. Insert the boot.flp floppy in the first floppy drive and boot the computer. The original install menu will be displayed on the screen. Select the Fixit--Repair mode with CDROM or floppy. option. Insert the fixit.flp when prompted. restore and the other programs that you need are located in /mnt2/rescue (/mnt2/stand for &os; versions older than 5.2). Recover each file system separately. mount root partition bsdlabel newfs Try to mount (e.g. mount /dev/da0a /mnt) the root partition of your first disk. If the bsdlabel was damaged, use bsdlabel to re-partition and label the disk to match the label that you printed and saved. Use newfs to re-create the file systems. Re-mount the root partition of the floppy read-write (mount -u -o rw /mnt). Use your backup program and backup tapes to recover the data for this file system (e.g. restore vrf /dev/sa0). Unmount the file system (e.g. umount /mnt). Repeat for each file system that was damaged. Once your system is running, backup your data onto new tapes. Whatever caused the crash or data loss may strike again. Another hour spent now may save you from further distress later. * I Did Not Prepare for the Disaster, What Now? ]]> Marc Fonvieille Reorganized and enhanced by Network, Memory, and File-Backed File Systems virtual disks disks virtual Aside from the disks you physically insert into your computer: floppies, CDs, hard drives, and so forth; other forms of disks are understood by FreeBSD - the virtual disks. NFS Coda disks memory These include network file systems such as the Network File System and Coda, memory-based file systems and file-backed file systems. According to the FreeBSD version you run, you will have to use different tools for creation and use of file-backed and memory-based file systems. Use &man.devfs.5; to allocate device nodes transparently for the user. File-Backed File System disks file-backed The utility &man.mdconfig.8; is used to configure and enable memory disks, &man.md.4;, under FreeBSD. To use &man.mdconfig.8;, you have to load &man.md.4; module or to add the support in your kernel configuration file: device md The &man.mdconfig.8; command supports three kinds of memory backed virtual disks: memory disks allocated with &man.malloc.9;, memory disks using a file or swap space as backing. One possible use is the mounting of floppy or CD images kept in files. To mount an existing file system image: Using <command>mdconfig</command> to Mount an Existing File System Image &prompt.root; mdconfig -a -t vnode -f diskimage -u 0 &prompt.root; mount /dev/md0 /mnt To create a new file system image with &man.mdconfig.8;: Creating a New File-Backed Disk with <command>mdconfig</command> &prompt.root; dd if=/dev/zero of=newimage bs=1k count=5k 5120+0 records in 5120+0 records out &prompt.root; mdconfig -a -t vnode -f newimage -u 0 &prompt.root; bsdlabel -w md0 auto &prompt.root; newfs md0a /dev/md0a: 5.0MB (10224 sectors) block size 16384, fragment size 2048 using 4 cylinder groups of 1.25MB, 80 blks, 192 inodes. super-block backups (for fsck -b #) at: 160, 2720, 5280, 7840 &prompt.root; mount /dev/md0a /mnt &prompt.root; df /mnt Filesystem 1K-blocks Used Avail Capacity Mounted on /dev/md0a 4710 4 4330 0% /mnt If you do not specify the unit number with the option, &man.mdconfig.8; will use the &man.md.4; automatic allocation to select an unused device. The name of the allocated unit will be output on stdout like md4. For more details about &man.mdconfig.8;, please refer to the manual page. The utility &man.mdconfig.8; is very useful, however it asks many command lines to create a file-backed file system. FreeBSD also comes with a tool called &man.mdmfs.8;, this program configures a &man.md.4; disk using &man.mdconfig.8;, puts a UFS file system on it using &man.newfs.8;, and mounts it using &man.mount.8;. For example, if you want to create and mount the same file system image as above, simply type the following: Configure and Mount a File-Backed Disk with <command>mdmfs</command> &prompt.root; dd if=/dev/zero of=newimage bs=1k count=5k 5120+0 records in 5120+0 records out &prompt.root; mdmfs -F newimage -s 5m md0 /mnt &prompt.root; df /mnt Filesystem 1K-blocks Used Avail Capacity Mounted on /dev/md0 4718 4 4338 0% /mnt If you use the option without unit number, &man.mdmfs.8; will use &man.md.4; auto-unit feature to automatically select an unused device. For more details about &man.mdmfs.8;, please refer to the manual page. Memory-Based File System disks memory file system For a memory-based file system the swap backing should normally be used. Using swap backing does not mean that the memory disk will be swapped out to disk by default, but merely that the memory disk will be allocated from a memory pool which can be swapped out to disk if needed. It is also possible to create memory-based disk which are &man.malloc.9; backed, but using malloc backed memory disks, especially large ones, can result in a system panic if the kernel runs out of memory. Creating a New Memory-Based Disk with <command>mdconfig</command> &prompt.root; mdconfig -a -t malloc -s 5m -u 1 &prompt.root; newfs -U md1 /dev/md1: 5.0MB (10240 sectors) block size 16384, fragment size 2048 using 4 cylinder groups of 1.27MB, 81 blks, 256 inodes. with soft updates super-block backups (for fsck -b #) at: 32, 2624, 5216, 7808 &prompt.root; mount /dev/md1 /mnt &prompt.root; df /mnt Filesystem 1K-blocks Used Avail Capacity Mounted on /dev/md1 4846 2 4458 0% /mnt Creating a New Memory-Based Disk with <command>mdmfs</command> &prompt.root; mdmfs -M -s 5m md2 /mnt &prompt.root; df /mnt Filesystem 1K-blocks Used Avail Capacity Mounted on /dev/md2 4846 2 4458 0% /mnt Instead of using a &man.malloc.9; backed file system, it is possible to use swap, for that just replace with in the command line of &man.mdconfig.8;. The &man.mdmfs.8; utility by default (without ) creates a swap-based disk. For more details, please refer to &man.mdconfig.8; and &man.mdmfs.8; manual pages. Detaching a Memory Disk from the System disks detaching a memory disk When a memory-based or file-based file system is not used, you should release all resources to the system. The first thing to do is to unmount the file system, then use &man.mdconfig.8; to detach the disk from the system and release the resources. For example to detach and free all resources used by /dev/md4: &prompt.root; mdconfig -d -u 4 It is possible to list information about configured &man.md.4; devices in using the command mdconfig -l. Tom Rhodes Contributed by File System Snapshots file systems snapshots FreeBSD offers a feature in conjunction with Soft Updates: File system snapshots. Snapshots allow a user to create images of specified file systems, and treat them as a file. Snapshot files must be created in the file system that the action is performed on, and a user may create no more than 20 snapshots per file system. Active snapshots are recorded in the superblock so they are persistent across unmount and remount operations along with system reboots. When a snapshot is no longer required, it can be removed with the standard &man.rm.1; command. Snapshots may be removed in any order, however all the used space may not be acquired because another snapshot will possibly claim some of the released blocks. The un-alterable file flag is set by &man.mksnap.ffs.8; after initial creation of a snapshot file. The &man.unlink.1; command makes an exception for snapshot files since it allows them to be removed. Snapshots are created with the &man.mount.8; command. To place a snapshot of /var in the file /var/snapshot/snap use the following command: &prompt.root; mount -u -o snapshot /var/snapshot/snap /var Alternatively, you can use &man.mksnap.ffs.8; to create a snapshot: &prompt.root; mksnap_ffs /var /var/snapshot/snap One can find snapshot files on a file system (e.g. /var) by using the &man.find.1; command: &prompt.root; find /var -flags snapshot Once a snapshot has been created, it has several uses: Some administrators will use a snapshot file for backup purposes, because the snapshot can be transfered to CDs or tape. File integrity, &man.fsck.8; may be ran on the snapshot. Assuming that the file system was clean when it was mounted, you should always get a clean (and unchanging) result. This is essentially what the background &man.fsck.8; process does. Run the &man.dump.8; utility on the snapshot. A dump will be returned that is consistent with the file system and the timestamp of the snapshot. &man.dump.8; can also take a snapshot, create a dump image and then remove the snapshot in one command using the flag. &man.mount.8; the snapshot as a frozen image of the file system. To &man.mount.8; the snapshot /var/snapshot/snap run: &prompt.root; mdconfig -a -t vnode -f /var/snapshot/snap -u 4 &prompt.root; mount -r /dev/md4 /mnt You can now walk the hierarchy of your frozen /var file system mounted at /mnt. Everything will initially be in the same state it was during the snapshot creation time. The only exception is that any earlier snapshots will appear as zero length files. When the use of a snapshot has delimited, it can be unmounted with: &prompt.root; umount /mnt &prompt.root; mdconfig -d -u 4 For more information about and file system snapshots, including technical papers, you can visit Marshall Kirk McKusick's website at . - File System Quotas + 磁碟空間配額(Quota) accounting disk space disk quotas - Quotas are an optional feature of the operating system that - allow you to limit the amount of disk space and/or the number of - files a user or members of a group may allocate on a per-file - system basis. This is used most often on timesharing systems where - it is desirable to limit the amount of resources any one user or - group of users may allocate. This will prevent one user or group - of users from consuming all of the available disk space. + 磁碟配額(Quota)屬於作業系統上的選用功能， + 可以用來限制使用者或群組的可用空間大小，或者檔案的總數多寡。 + 這功能通常用在多人共用的系統環境上， + 因為要限制各使用者或各群組所能運用的系統資源。 + 如此一來，就可避免磁碟空間被某使用者或某群組全部耗盡。 - Configuring Your System to Enable Disk Quotas + 啟用磁碟配額 - Before attempting to use disk quotas, it is necessary to make - sure that quotas are configured in your kernel. This is done by - adding the following line to your kernel configuration - file: + 在用磁碟配額之前，請先確認 kernel 已經有作相關設定，也就是 + kernel 設定檔要有下面這行： options QUOTA - The stock GENERIC kernel does not have - this enabled by default, so you will have to configure, build and - install a custom kernel in order to use disk quotas. Please refer - to for more information on kernel - configuration. + 預設的 GENERIC kernel 並不會加上這項， + 所以若要啟用就必需加上，並重新編譯、安裝 kernel。 kernel + 設定部分可參閱 的說明。 - Next you will need to enable disk quotas in - /etc/rc.conf. This is done by adding the - line: + 接著就是在 /etc/rc.conf 設定啟動磁碟配額。 + 請加上下列這行： enable_quotas="YES" disk quotas checking - For finer control over your quota startup, there is an - additional configuration variable available. Normally on bootup, - the quota integrity of each file system is checked by the - &man.quotacheck.8; program. The - &man.quotacheck.8; facility insures that the data in - the quota database properly reflects the data on the file system. - This is a very time consuming process that will significantly - affect the time your system takes to boot. If you would like to - skip this step, a variable in /etc/rc.conf - is made available for the purpose: + 為了能更完善的控管磁碟配額的啟動，還有一個設定可以用。 通常開機時， + &man.quotacheck.8; 程式會檢查各檔案系統上的配額。 + &man.quotacheck.8; 可以確保配額資料庫的資料與實際檔案系統的資料有符合。 + 但這功能也會在開機時，會對啟動時間造成相當明顯的影響。 + 若想跳過這步驟，則可以在 /etc/rc.conf 加上： check_quotas="NO" - Finally you will need to edit /etc/fstab - to enable disk quotas on a per-file system basis. This is where - you can either enable user or group quotas or both for all of your - file systems. + 最後，要記得改 /etc/fstab + 來啟用以檔案系統為對象的磁碟配額功能。 也可以啟用針對使用者或群組， + 或者兩者皆有之的磁碟配額。 - To enable per-user quotas on a file system, add the - option to the options field in the - /etc/fstab entry for the file system you want - to enable quotas on. For example: + 若要啟用針對使用者的配額，可以在 /etc/fstab + 內要設定的檔案系統加上 選項。 比如： /dev/da1s2g /home ufs rw,userquota 1 2 - Similarly, to enable group quotas, use the - option instead of - . To enable both user and - group quotas, change the entry as follows: + 同理若要啟用針對群組的配額，則把剛剛的 + 換成 即可。 而若要兩者同時啟用， + 那麼則是： /dev/da1s2g /home ufs rw,userquota,groupquota 1 2 - By default, the quota files are stored in the root directory of - the file system with the names quota.user and - quota.group for user and group quotas - respectively. See &man.fstab.5; for more - information. Even though the &man.fstab.5; manual page says that - you can specify - an alternate location for the quota files, this is not recommended - because the various quota utilities do not seem to handle this - properly. - - At this point you should reboot your system with your new - kernel. /etc/rc will automatically run the - appropriate commands to create the initial quota files for all of - the quotas you enabled in /etc/fstab, so - there is no need to manually create any zero length quota - files. - - In the normal course of operations you should not be required - to run the &man.quotacheck.8;, - &man.quotaon.8;, or &man.quotaoff.8; - commands manually. However, you may want to read their manual pages - just to be familiar with their operation. + 針對使用者以及群組的磁碟配額設定檔，預設分別會放在該檔案系統根目錄的 + quota.user 以及 quota.group + 。 細節部分請參閱 &man.fstab.5;。 + 雖然 &man.fstab.5; 提到可以為配額設定檔指定其他地方，但並不建議如此作， + 因為各種磁碟配額管理工具並不見得對這些預設值能隨之彈性變化。 + + 接下來就可以用新 kernel 來重開機。 /etc/rc + 會自動執行相關指令以對 /etc/fstab + 有設定配額管理的部分，作初始設定。 + 所以並不需要逐一手動產生相關空的配額設定檔。 + + 正常操作過程中，並不需要手動執行 &man.quotacheck.8;、&man.quotaon.8; + 、&man.quotaoff.8; 這些指令。 不過，若要更熟悉相關操作方式的話， + 或許可以閱讀相關的 manual 線上說明。 - Setting Quota Limits + 設定配額限制 disk quotas limits - Once you have configured your system to enable quotas, verify - that they really are enabled. An easy way to do this is to - run: + 一旦開始啟用配額管理之後，請記得確認是否有真的啟用。 + 可以打下列指令來作簡單檢查： &prompt.root; quota -v - You should see a one line summary of disk usage and current - quota limits for each file system that quotas are enabled - on. + 應該可以看到有關各檔案系統的配額限量， + 以及現在使用量的摘要訊息。 - You are now ready to start assigning quota limits with the - &man.edquota.8; command. + 現在可以開始用 &man.edquota.8; 來設定各磁碟配額的限制。 - You have several options on how to enforce limits on the - amount of disk space a user or group may allocate, and how many - files they may create. You may limit allocations based on disk - space (block quotas) or number of files (inode quotas) or a - combination of both. Each of these limits are further broken down - into two categories: hard and soft limits. + 有幾種選項可以用來限制使用者或群組所能運用的磁碟空間， + 以及所能建立的檔案數量多寡。 可以依磁碟空間(block 配額)或檔案數量 + (inode 配額)，或者搭配兩者一起設定。 而每種限制還可以細分為兩類： + hard(硬性)上限、soft(彈性)上限。 hard limit - A hard limit may not be exceeded. Once a user reaches his - hard limit he may not make any further allocations on the file - system in question. For example, if the user has a hard limit of - 500 kbytes on a file system and is currently using 490 kbytes, the - user can only allocate an additional 10 kbytes. Attempting to - allocate an additional 11 kbytes will fail. + 硬性上限是不能超過的。 一旦使用者達到硬性上限時， + 就無法在該檔案系統上繼續使用更多的使用空間了。 + 舉例來說，若有位使用者的硬性上限為 500 KB，而目前用了 490 KB， + 那麼他就只能再多用 10 KB 而已，若要新增的檔案有 11 KB 就會失敗。 soft limit - Soft limits, on the other hand, can be exceeded for a limited - amount of time. This period of time is known as the grace period, - which is one week by default. If a user stays over his or her - soft limit longer than the grace period, the soft limit will - turn into a hard limit and no further allocations will be allowed. - When the user drops back below the soft limit, the grace period - will be reset. - - The following is an example of what you might see when you run - the &man.edquota.8; command. When the - &man.edquota.8; command is invoked, you are placed into - the editor specified by the EDITOR environment - variable, or in the vi editor if the - EDITOR variable is not set, to allow you to edit - the quota limits. + 然而，彈性上限則可允許一定時間內的超額使用，這段期間稱為 + grace period(寬限期)，預設值是一週。 若使用者持續超額使用並超出 + grace period 而逾期，則彈性上限就會轉為硬性上限， + 而不允許該使用者繼續新增空間。 + 直到該使用者的空間已經清到低於彈性上限之後，才會重設 + grace period。 + + 下面則是使用 &man.edquota.8; 的例子。 在執行 &man.edquota.8; + 時，會進入設定磁碟配額上限的編輯器內，至於是哪一種編輯器則視您的 + EDITOR 環境變數而定，若沒設定 EDITOR + 的話，則會用 vi 編輯器。 &prompt.root; edquota -u test Quotas for user test: /usr: kbytes in use: 65, limits (soft = 50, hard = 75) inodes in use: 7, limits (soft = 50, hard = 60) /usr/var: kbytes in use: 0, limits (soft = 50, hard = 75) inodes in use: 0, limits (soft = 50, hard = 60) - You will normally see two lines for each file system that has - quotas enabled. One line for the block limits, and one line for - inode limits. Simply change the value you want updated to modify - the quota limit. For example, to raise this user's block limit - from a soft limit of 50 and a hard limit of 75 to a soft limit of - 500 and a hard limit of 600, change: + 一般來說，每個啟動了磁碟配額的檔案系統都會有兩行設定。 + 第一行是 block 上限，而另一行則是 inode 上限。 + 若要更改磁碟配額上限，只需要修改後面的數值即可。 舉例來說， + 要增加這位使用者的 block 上限部分：把彈性上限 50 調為 500， + 硬性上限則由 75 調為 600 ，只需修改下面這行： /usr: kbytes in use: 65, limits (soft = 50, hard = 75) - to: + 改為下列： /usr: kbytes in use: 65, limits (soft = 500, hard = 600) - The new quota limits will be in place when you exit the - editor. + 然後存檔離開後，新的配額設定就會立即生效。 - Sometimes it is desirable to set quota limits on a range of - UIDs. This can be done by use of the option - on the &man.edquota.8; command. First, assign the - desired quota limit to a user, and then run - edquota -p protouser startuid-enduid. For - example, if user test has the desired quota - limits, the following command can be used to duplicate those quota - limits for UIDs 10,000 through 19,999: + 有時候會想一次改大範圍 UID 的帳號設定，這時可以用 &man.edquota.8; + 的 參數功能來完成。 首先， + 把某個帳號調為想要的相關配額，然後可以用 + edquota -p protouser startuid-enduid 之類的方式來改。 + 舉例來說，假設 test 這帳號已經設定好相關配額， + 然後要改的對象為 UID 從 10,000 到 19,999 的帳號， + 那麼就可以下列指令來設定同樣的配額： &prompt.root; edquota -p test 10000-19999 - For more information see &man.edquota.8; manual page. + 細節說明請參閱 &man.edquota.8;。 - Checking Quota Limits and Disk Usage + 檢查磁碟配額設定、磁碟使用量 disk quotas checking - You can use either the &man.quota.1; or the - &man.repquota.8; commands to check quota limits and - disk usage. The &man.quota.1; command can be used to - check individual user or group quotas and disk usage. A user - may only examine his own quota, and the quota of a group he - is a member of. Only the super-user may view all user and group - quotas. The - &man.repquota.8; command can be used to get a summary - of all quotas and disk usage for file systems with quotas - enabled. - - The following is some sample output from the - quota -v command for a user that has quota - limits on two file systems. + 可以用 &man.quota.1; 或 &man.repquota.8; 來檢查磁碟配額設定， + 以及磁碟使用量。 &man.quota.1; 可用來檢查單一使用者或群組的磁碟配額、 + 磁碟使用量。 不過一般帳號只能查自己的以及自己群組的磁碟配額、 + 磁碟使用量，只有系統管理者帳號才能察看所有使用者、 + 群組的配額設定與使用量。 而 &man.repquota.8; + 則可以看到所有已啟動磁碟配額的檔案系統設定、磁碟使用量摘要。 + + 下面例子則是在兩個有配額設定的檔案系統上，打 + quota -v 的顯示結果： Disk quotas for user test (uid 1002): Filesystem usage quota limit grace files quota limit grace /usr 65* 50 75 5days 7 50 60 /usr/var 0 50 75 0 50 60 grace period - On the /usr file system in the above - example, this user is currently 15 kbytes over the soft limit of - 50 kbytes and has 5 days of the grace period left. Note the - asterisk * which indicates that the user is - currently over his quota limit. - - Normally file systems that the user is not using any disk - space on will not show up in the output from the - &man.quota.1; command, even if he has a quota limit - assigned for that file system. The option - will display those file systems, such as the - /usr/var file system in the above - example. + 在上面這例中，該使用者在 /usr 的彈性配額是 + 50 KB，實際上已經超額多用 15 KB，而 grace period 還有 5 天就逾期。 + 請注意這個星號 * + 是表示目前該使用者已經超越其配額的彈性上限了。 + + 一般來說，若使用者並沒有用到某個檔案系統， + 那麼就算該檔案有啟用磁碟配額，在 &man.quota.1; 也不會顯示出來。 + 而 參數則可以把這些檔案系統都全部列出來， + 比如上例中的 /usr/var。 - Quotas over NFS + 透過 NFS 使用磁碟配額 NFS - Quotas are enforced by the quota subsystem on the NFS server. - The &man.rpc.rquotad.8; daemon makes quota information available - to the &man.quota.1; command on NFS clients, allowing users on - those machines to see their quota statistics. + NFS server 端可以強制以 quota subsystem(配額子系統)來用磁碟配額。 + 而 NFS client 端則可以透過 &man.rpc.rquotad.8; daemon 來讓 &man.quota.1; + 指令抓到相關配額資料，也就可以讓 client + 端的使用者察看其配額的統計資料。 - Enable rpc.rquotad in - /etc/inetd.conf like so: + 若要啟用 rpc.rquotad，可以在 + /etc/inetd.conf 加上下列類似設定： rquotad/1 dgram rpc/udp wait root /usr/libexec/rpc.rquotad rpc.rquotad - Now restart inetd: + 然後重啟 inetd 即可： &prompt.root; kill -HUP `cat /var/run/inetd.pid` Lucky Green Contributed by
shamrock@cypherpunks.to
 Encrypting Disk Partitions disks encrypting FreeBSD offers excellent online protections against unauthorized data access. File permissions and Mandatory Access Control (MAC) (see ) help prevent unauthorized third-parties from accessing data while the operating system is active and the computer is powered up. However, the permissions enforced by the operating system are irrelevant if an attacker has physical access to a computer and can simply move the computer's hard drive to another system to copy and analyze the sensitive data. Regardless of how an attacker may have come into possession of a hard drive or powered-down computer, both GEOM Based Disk Encryption (gbde) and geli cryptographic subsystems in &os; are able to protect the data on the computer's file systems against even highly-motivated attackers with significant resources. Unlike cumbersome encryption methods that encrypt only individual files, gbde and geli transparently encrypt entire file systems. No cleartext ever touches the hard drive's platter. Disk Encryption with <application>gbde</application> Become <username>root</username> Configuring gbde requires super-user privileges. &prompt.user; su - Password: Add &man.gbde.4; Support to the Kernel Configuration File Add the following line to the kernel configuration file: options GEOM_BDE Rebuild the kernel as described in . Reboot into the new kernel. Preparing the Encrypted Hard Drive The following example assumes that you are adding a new hard drive to your system that will hold a single encrypted partition. This partition will be mounted as /private. gbde can also be used to encrypt /home and /var/mail, but this requires more complex instructions which exceed the scope of this introduction. Add the New Hard Drive Install the new drive to the system as explained in . For the purposes of this example, a new hard drive partition has been added as /dev/ad4s1c. The /dev/ad0s1* devices represent existing standard FreeBSD partitions on the example system. &prompt.root; ls /dev/ad* /dev/ad0 /dev/ad0s1b /dev/ad0s1e /dev/ad4s1 /dev/ad0s1 /dev/ad0s1c /dev/ad0s1f /dev/ad4s1c /dev/ad0s1a /dev/ad0s1d /dev/ad4 Create a Directory to Hold gbde Lock Files &prompt.root; mkdir /etc/gbde The gbde lock file contains information that gbde requires to access encrypted partitions. Without access to the lock file, gbde will not be able to decrypt the data contained in the encrypted partition without significant manual intervention which is not supported by the software. Each encrypted partition uses a separate lock file. Initialize the gbde Partition A gbde partition must be initialized before it can be used. This initialization needs to be performed only once: &prompt.root; gbde init /dev/ad4s1c -i -L /etc/gbde/ad4s1c &man.gbde.8; will open your editor, permitting you to set various configuration options in a template. For use with UFS1 or UFS2, set the sector_size to 2048: $FreeBSD: src/sbin/gbde/template.txt,v 1.1 2002/10/20 11:16:13 phk Exp $ # # Sector size is the smallest unit of data which can be read or written. # Making it too small decreases performance and decreases available space. # Making it too large may prevent filesystems from working. 512 is the # minimum and always safe. For UFS, use the fragment size # sector_size = 2048 [...] &man.gbde.8; will ask you twice to type the passphrase that should be used to secure the data. The passphrase must be the same both times. gbde's ability to protect your data depends entirely on the quality of the passphrase that you choose. For tips on how to select a secure passphrase that is easy to remember, see the Diceware Passphrase website. The gbde init command creates a lock file for your gbde partition that in this example is stored as /etc/gbde/ad4s1c. gbde lock files must be backed up together with the contents of any encrypted partitions. While deleting a lock file alone cannot prevent a determined attacker from decrypting a gbde partition, without the lock file, the legitimate owner will be unable to access the data on the encrypted partition without a significant amount of work that is totally unsupported by &man.gbde.8; and its designer. Attach the Encrypted Partition to the Kernel &prompt.root; gbde attach /dev/ad4s1c -l /etc/gbde/ad4s1c You will be asked to provide the passphrase that you selected during the initialization of the encrypted partition. The new encrypted device will show up in /dev as /dev/device_name.bde: &prompt.root; ls /dev/ad* /dev/ad0 /dev/ad0s1b /dev/ad0s1e /dev/ad4s1 /dev/ad0s1 /dev/ad0s1c /dev/ad0s1f /dev/ad4s1c /dev/ad0s1a /dev/ad0s1d /dev/ad4 /dev/ad4s1c.bde Create a File System on the Encrypted Device Once the encrypted device has been attached to the kernel, you can create a file system on the device. To create a file system on the encrypted device, use &man.newfs.8;. Since it is much faster to initialize a new UFS2 file system than it is to initialize the old UFS1 file system, using &man.newfs.8; with the option is recommended. &prompt.root; newfs -U -O2 /dev/ad4s1c.bde The &man.newfs.8; command must be performed on an attached gbde partition which is identified by a *.bde extension to the device name. Mount the Encrypted Partition Create a mount point for the encrypted file system. &prompt.root; mkdir /private Mount the encrypted file system. &prompt.root; mount /dev/ad4s1c.bde /private Verify That the Encrypted File System is Available The encrypted file system should now be visible to &man.df.1; and be available for use. &prompt.user; df -H Filesystem Size Used Avail Capacity Mounted on /dev/ad0s1a 1037M 72M 883M 8% / /devfs 1.0K 1.0K 0B 100% /dev /dev/ad0s1f 8.1G 55K 7.5G 0% /home /dev/ad0s1e 1037M 1.1M 953M 0% /tmp /dev/ad0s1d 6.1G 1.9G 3.7G 35% /usr /dev/ad4s1c.bde 150G 4.1K 138G 0% /private Mounting Existing Encrypted File Systems After each boot, any encrypted file systems must be re-attached to the kernel, checked for errors, and mounted, before the file systems can be used. The required commands must be executed as user root. Attach the gbde Partition to the Kernel &prompt.root; gbde attach /dev/ad4s1c -l /etc/gbde/ad4s1c You will be asked to provide the passphrase that you selected during initialization of the encrypted gbde partition. Check the File System for Errors Since encrypted file systems cannot yet be listed in /etc/fstab for automatic mounting, the file systems must be checked for errors by running &man.fsck.8; manually before mounting. &prompt.root; fsck -p -t ffs /dev/ad4s1c.bde Mount the Encrypted File System &prompt.root; mount /dev/ad4s1c.bde /private The encrypted file system is now available for use. Automatically Mounting Encrypted Partitions It is possible to create a script to automatically attach, check, and mount an encrypted partition, but for security reasons the script should not contain the &man.gbde.8; password. Instead, it is recommended that such scripts be run manually while providing the password via the console or &man.ssh.1;. As of &os; 5.2-RELEASE, there is a new rc.d script provided. Arguments for this script can be passed via &man.rc.conf.5;, for example: gbde_autoattach_all="YES" gbde_devices="ad4s1c" This will require that the gbde passphrase be entered at boot time. After typing the correct passphrase, the gbde encrypted partition will be mounted automatically. This can be very useful when using gbde on notebooks. Cryptographic Protections Employed by gbde &man.gbde.8; encrypts the sector payload using 128-bit AES in CBC mode. Each sector on the disk is encrypted with a different AES key. For more information on gbde's cryptographic design, including how the sector keys are derived from the user-supplied passphrase, see &man.gbde.4;. Compatibility Issues &man.sysinstall.8; is incompatible with gbde-encrypted devices. All *.bde devices must be detached from the kernel before starting &man.sysinstall.8; or it will crash during its initial probing for devices. To detach the encrypted device used in our example, use the following command: &prompt.root; gbde detach /dev/ad4s1c Also note that, as &man.vinum.4; does not use the &man.geom.4; subsystem, you cannot use gbde with vinum volumes. Daniel Gerzo Contributed by Disk Encryption with <command>geli</command> A new cryptographic GEOM class is available as of &os; 6.0 - geli. It is currently being developed by &a.pjd;. Geli is different to gbde; it offers different features and uses a different scheme for doing cryptographic work. The most important features of &man.geli.8; are: Utilizes the &man.crypto.9; framework — when cryptographic hardware is available, geli will use it automatically. Supports multiple cryptographic algorithms (currently AES, Blowfish, and 3DES). Allows the root partition to be encrypted. The passphrase used to access the encrypted root partition will be requested during the system boot. Allows the use of two independent keys (e.g. a key and a company key). geli is fast - performs simple sector-to-sector encryption. Allows backup and restore of Master Keys. When a user has to destroy his keys, it will be possible to get access to the data again by restoring keys from the backup. Allows to attach a disk with a random, one-time key — useful for swap partitions and temporary file systems. More geli features can be found in the &man.geli.8; manual page. The next steps will describe how to enable support for geli in the &os; kernel and will explain how to create a new geli encryption provider. At the end it will be demonstrated how to create an encrypted swap partition using features provided by geli. In order to use geli, you must be running &os; 6.0-RELEASE or later. Super-user privileges will be required since modifications to the kernel are necessary. Adding <command>geli</command> Support to the Kernel Configuration File Add the following lines to the kernel configuration file: options GEOM_ELI device crypto Rebuild the kernel as described in . Alternatively, the geli module can be loaded at boot time. Add the following line to the /boot/loader.conf: geom_eli_load="YES" &man.geli.8; should now be supported by the kernel. Generating the Master Key The following example will describe how to generate a key file, which will be used as part of the Master Key for the encrypted provider mounted under /private. The key file will provide some random data used to encrypt the Master Key. The Master Key will be protected by a passphrase as well. Provider's sector size will be 4kB big. Furthermore, the discussion will describe how to attach the geli provider, create a file system on it, how to mount it, how to work with it, and finally how to detach it. It is recommended to use a bigger sector size (like 4kB) for better performance. The Master Key will be protected with a passphrase and the data source for key file will be /dev/random. The sector size of /dev/da2.eli, which we call provider, will be 4kB. &prompt.root; dd if=/dev/random of=/root/da2.key bs=64 count=1 &prompt.root; geli init -s 4096 -K /root/da2.key /dev/da2 Enter new passphrase: Reenter new passphrase: It is not mandatory that both a passphrase and a key file are used; either method of securing the Master Key can be used in isolation. If key file is given as -, standard input will be used. This example shows how more than one key file can be used. &prompt.root; cat keyfile1 keyfile2 keyfile3 | geli init -K - /dev/da2 Attaching the Provider with the generated Key &prompt.root; geli attach -k /root/da2.key /dev/da2 Enter passphrase: The new plaintext device will be named /dev/da2.eli. &prompt.root; ls /dev/da2* /dev/da2 /dev/da2.eli Creating the new File System &prompt.root; dd if=/dev/random of=/dev/da2.eli bs=1m &prompt.root; newfs /dev/da2.eli &prompt.root; mount /dev/da2.eli /private The encrypted file system should be visible to &man.df.1; and be available for use now. &prompt.root; df -H Filesystem Size Used Avail Capacity Mounted on /dev/ad0s1a 248M 89M 139M 38% / /devfs 1.0K 1.0K 0B 100% /dev /dev/ad0s1f 7.7G 2.3G 4.9G 32% /usr /dev/ad0s1d 989M 1.5M 909M 0% /tmp /dev/ad0s1e 3.9G 1.3G 2.3G 35% /var /dev/da2.eli 150G 4.1K 138G 0% /private Unmounting and Detaching the Provider Once the work on the encrypted partition is done, and the /private partition is no longer needed, it is prudent to consider unmounting and detaching the geli encrypted partition from the kernel. &prompt.root; umount /private &prompt.root; geli detach da2.eli More information about the use of &man.geli.8; can be found in the manual page. Encrypting a Swap Partition The following example demonstrates how to create a geli encrypted swap partition. &prompt.root; dd if=/dev/random of=/dev/ad0s1b bs=1m &prompt.root; geli onetime -d -a 3des ad0s1b &prompt.root; swapon /dev/ad0s1b.eli Using the <filename>geli</filename> <filename>rc.d</filename> Script geli comes with a rc.d script which can be used to simplify the usage of geli. An example of configuring geli through &man.rc.conf.5; follows: geli_devices="da2" geli_da2_flags="-p -k /root/da2.key" This will configure /dev/da2 as a geli provider of which the Master Key file is located in /root/da2.key, and geli will not use a passphrase when attaching the provider (note that this can only be used if -P was given during the geli init phase). The system will detach the geli provider from the kernel before the system shuts down. More information about configuring rc.d is provided in the rc.d section of the Handbook. Christian Brüffer Written by Encrypting Swap Space swap encrypting Swap encryption in &os; is easy to configure and has been available since &os; 5.3-RELEASE. Depending on which version of &os; is being used, different options are available and configuration can vary slightly. From &os; 6.0-RELEASE onwards, the &man.gbde.8; or &man.geli.8; encryption systems can be used for swap encryption. With earlier versions, only &man.gbde.8; is available. Both systems use the encswap rc.d script. The previous section, Encrypting Disk Partitions, includes a short discussion on the different encryption systems. Why should Swap be Encrypted? Like the encryption of disk partitions, encryption of swap space is done to protect sensitive information. Imagine an application that e.g. deals with passwords. As long as these passwords stay in physical memory, all is well. However, if the operating system starts swapping out memory pages to free space for other applications, the passwords may be written to the disk platters unencrypted and easy to retrieve for an adversary. Encrypting swap space can be a solution for this scenario. Preparation For the remainder of this section, ad0s1b will be the swap partition. Up to this point the swap has been unencrypted. It is possible that there are already passwords or other sensitive data on the disk platters in cleartext. To rectify this, the data on the swap partition should be overwritten with random garbage: &prompt.root; dd if=/dev/random of=/dev/ad0s1b bs=1m Swap Encryption with &man.gbde.8; If &os; 6.0-RELEASE or newer is being used, the .bde suffix should be added to the device in the respective /etc/fstab swap line: # Device Mountpoint FStype Options Dump Pass# /dev/ad0s1b.bde none swap sw 0 0 For systems prior to &os; 6.0-RELEASE, the following line in /etc/rc.conf is also needed: gbde_swap_enable="YES" Swap Encryption with &man.geli.8; Alternatively, the procedure for using &man.geli.8; for swap encryption is similar to that of using &man.gbde.8;. The .eli suffix should be added to the device in the respective /etc/fstab swap line: # Device Mountpoint FStype Options Dump Pass# /dev/ad0s1b.eli none swap sw 0 0 &man.geli.8; uses the AES algorithm with a key length of 256 bit by default. Optionally, these defaults can be altered using the geli_swap_flags option in /etc/rc.conf. The following line tells the encswap rc.d script to create &man.geli.8; swap partitions using the Blowfish algorithm with a key length of 128 bit, a sectorsize of 4 kilobytes and the detach on last close option set: geli_swap_flags="-a blowfish -l 128 -s 4096 -d" Please refer to the description of the onetime command in the &man.geli.8; manual page for a list of possible options. Verifying that it Works Once the system has been rebooted, proper operation of the encrypted swap can be verified using the swapinfo command. If &man.gbde.8; is being used: &prompt.user; swapinfo Device 1K-blocks Used Avail Capacity /dev/ad0s1b.bde 542720 0 542720 0% If &man.geli.8; is being used: &prompt.user; swapinfo Device 1K-blocks Used Avail Capacity /dev/ad0s1b.eli 542720 0 542720 0%