Date: Thu, 30 Jan 2014 21:06:20 +0000 (UTC) From: Dru Lavigne <dru@FreeBSD.org> To: doc-committers@freebsd.org, svn-doc-all@freebsd.org, svn-doc-head@freebsd.org Subject: svn commit: r43698 - head/en_US.ISO8859-1/books/handbook/disks Message-ID: <201401302106.s0UL6KVB034022@svn.freebsd.org>
next in thread | raw e-mail | index | archive | help
Author: dru Date: Thu Jan 30 21:06:20 2014 New Revision: 43698 URL: http://svnweb.freebsd.org/changeset/doc/43698 Log: Next pass through this chapter. Clarified text in File System Backups Redid examples in Directory Backups to show how 3 utils differ when creating similar backups. New examples are aimed at what a new user is likely to do. More complex examples should be added. Next pass will finish this section, to be followed by white space fix-ups. Sponsored by: iXsystems Modified: head/en_US.ISO8859-1/books/handbook/disks/chapter.xml Modified: head/en_US.ISO8859-1/books/handbook/disks/chapter.xml ============================================================================== --- head/en_US.ISO8859-1/books/handbook/disks/chapter.xml Thu Jan 30 19:00:09 2014 (r43697) +++ head/en_US.ISO8859-1/books/handbook/disks/chapter.xml Thu Jan 30 21:06:20 2014 (r43698) @@ -1123,12 +1123,12 @@ cd0: Attempt to query device size failed <note> <para>In order to support working files larger than 4.38GB, an - UDF/ISO-9660 hybrid filesystem must be created by passing + UDF/ISO-9660 hybrid file system must be created by passing <option>-udf -iso-level 3</option> to &man.mkisofs.8; and all related programs, such as &man.growisofs.1;. This is required only when creating an ISO image file or when writing files directly to a disk. Since a disk created this - way must be mounted as an UDF filesystem with + way must be mounted as an UDF file system with &man.mount.udf.8;, it will be usable only on an UDF aware operating system. Otherwise it will look as if it contains corrupted files.</para> @@ -1610,7 +1610,7 @@ cd0: Attempt to query device size failed </listitem> <listitem> - <para>Filesystem snapshots, which are useful for restoring + <para>File system snapshots, which are useful for restoring deleted files or previous versions of files.</para> </listitem> @@ -1650,24 +1650,20 @@ cd0: Attempt to query device size failed <primary><command>restore</command></primary> </indexterm> - <para>The traditional &unix; backup programs are - <command>dump</command> and <command>restore</command>. 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. Unlike other backup software, - <command>dump</command> 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. - <command>dump</command> does not write files and directories, - but rather writes the raw data blocks that comprise files and - directories. When used to extract data, - <command>restore</command> stores temporary files in - <filename>/tmp/</filename> by default. When using a recovery - disk with a small <filename>/tmp</filename>, set - <envar>TMPDIR</envar> to a directory with more free space in - order for the restore to succeed.</para> + <para>The traditional &unix; programs for backing up a file + system are &man.dump.8;, which creates the backup, and + &man.restore.8;, which restores the backup. These utilities + work at the disk block level, below the + abstractions of the files, links, and directories that are created + by file systems. Unlike other backup software, + <command>dump</command> backs up an entire file system and + is unable to backup only part of a file system or + a directory tree that spans multiple file systems. + Instead of writing files and directories, <command>dump</command> + writes the raw data blocks that comprise files and + directories.</para> - <note> + <note> <para>If <command>dump</command> is used on the root directory, it will not back up <filename>/home</filename>, <filename>/usr</filename> or many other @@ -1675,39 +1671,34 @@ cd0: Attempt to query device size failed file systems or symbolic links into those file systems.</para> </note> + + <para>When used to restore data, + <command>restore</command> stores temporary files in + <filename>/tmp/</filename> by default. When using a recovery + disk with a small <filename>/tmp</filename>, set + <envar>TMPDIR</envar> to a directory with more free space in + order for the restore to succeed.</para> - <para><command>dump</command> has quirks that remain from its + <para>When using <command>dump</command>, be aware that some quirks 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.</para> + default parameters assume a backup to a 9-track tape, rather than + to another media or the high-density tapes available today. + These defaults must be overridden on the command line.</para> <indexterm> <primary><filename>.rhosts</filename></primary> </indexterm> - <para>It is also possible to backup data across the network to a - tape drive attached to another computer with - <command>rdump</command> and <command>rrestore</command>. - 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 <filename>.rhosts</filename> on - the remote computer. The arguments to - <command>rdump</command> and <command>rrestore</command> must - be suitable to use on the remote computer. For example, to - <command>rdump</command> from a &os; computer to an Exabyte - tape drive connected to a host called - <systemitem>komodo</systemitem>, use:</para> - - <screen>&prompt.root; <userinput>/sbin/rdump 0dsbfu 54000 13000 126 komodo:/dev/nsa8 /dev/da0a 2>&1</userinput></screen> - - <para>There are security implications to allowing - <filename>.rhosts</filename> authentication, so use - with caution.</para> - - <para>It is also possible to use <command>dump</command> and - <command>restore</command> in a more secure fashion over - <command>ssh</command>.</para> + <para>It is possible to backup a file system across the network to a + another system or to a tape drive attached to another computer. + While the &man.rdump.8; and &man.rrestore.8; utilities can be + used for this purpose, they are not considered to be secure.</para> + + <para>Instead, one can use <command>dump</command> and + <command>restore</command> in a more secure fashion over an + <acronym>SSH</acronym> connection. This example creates a + full, compressed backup of the <filename>/usr</filename> file + system and sends the backup file to the specified host over a + <acronym>SSH</acronym> connection.</para> <example> <title>Using <command>dump</command> over @@ -1717,7 +1708,9 @@ cd0: Attempt to query device size failed targetuser@targetmachine.example.com dd of=/mybigfiles/dump-usr-l0.gz</userinput></screen> </example> - <para>Or, use the built-in <envar>RSH</envar>:</para> + <para>This example sets <envar>RSH</envar> in order to write the + the backup to a tape drive on a remote system over a + <acronym>SSH</acronym> connection:</para> <example> <title>Using <command>dump</command> over @@ -1738,60 +1731,73 @@ cd0: Attempt to query device size failed <para>Several built-in utilities are available for backing up and restoring specified files and directories as needed.</para> - - <para>&man.tar.1; also dates back to Version 6 of AT&T - &unix;, circa 1975. <command>tar</command> operates in - cooperation with the file system and writes files and - directories to tape. <command>tar</command> 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 <command>cpio</command> uses.</para> + + <para>A good choice for making a backup of all of the files in a + directory is &man.tar.1;. This utility dates back to Version 6 of AT&T + &unix; and by default assumes a recursive backup to a local tape + device. Switches can be used to instead specify the name of + a backup file.</para> <indexterm><primary><command>tar</command></primary></indexterm> - <para>To <command>tar</command> to an Exabyte tape drive - connected to a host called - <systemitem>komodo</systemitem>:</para> + <para>This example creates a compressed backup of the current + directory and saves it to + <filename>/tmp/mybackup.tgz</filename>. When creating a + backup file, make sure that the backup is not saved to the + same directory that is being backed up.</para> + + <example> + <title>Backing Up the Current Directory With + <command>tar</command></title> + + <screen>&prompt.root; <userinput>tar czvf /tmp/mybackup.tgz . </userinput></screen> + </example> + + <para>To restore the entire backup, <command>cd</command> into + the directory to restore into and specify the name of the + backup. Note that this will overwrite any newer versions of + files in the restore directory. When in doubt, restore to a + temporary directory or specify the name of the file within the + backup to restore.</para> + + <example> + <title>Restoring Up the Current Directory With + <command>tar</command></title> - <screen>&prompt.root; <userinput>tar cf - . | rsh komodo dd of=tape-device obs=20b</userinput></screen> + <screen>&prompt.root; <userinput>tar xzvf /tmp/mybackup.tgz</userinput></screen> + </example> - <para>When backing up over an insecure network, instead use - <command>ssh</command>.</para> + <para>There are dozens of available switches which are described + in &man.tar.1;. This utility also supports the use of exclude + patterns to specify which files should not be included when + backing up the specified directory or restoring files from a + backup.</para> <indexterm> <primary>backup software</primary> <secondary><command>cpio</command></secondary> </indexterm> - <para>&man.cpio.1; is the original &unix; file interchange tape - program for magnetic media. <command>cpio</command> includes - options to perform byte-swapping, write a number of different - archive formats, and pipe the data to other programs. This - last feature makes <command>cpio</command> an excellent choice - for installation media. <command>cpio</command> does not know - how to walk the directory tree and a list of files must be - provided through <filename>stdin</filename>.</para> - - <indexterm> - <primary><command>cpio</command></primary> - </indexterm> - - <para>Since <command>cpio</command> does not support backups - across the network, use a pipeline and <command>ssh</command> - to send the data to a remote tape drive.</para> - - <screen>&prompt.root; <userinput>for f in directory_list; do</userinput> -<userinput>find $f >> backup.list</userinput> -<userinput>done</userinput> -&prompt.root; <userinput>cpio -v -o --format=newc < backup.list | ssh user@host "cat > backup_device"</userinput></screen> - - <para>Where <replaceable>directory_list</replaceable> is the - list of directories to back up, - <replaceable>user</replaceable>@<replaceable>host</replaceable> - is the user/hostname combination that will be performing the - backups, and <replaceable>backup_device</replaceable> is where - the backups should be written to, such as - <filename>/dev/nsa0</filename>).</para> + <para>To create a backup using a specified list of files and + directories, &man.cpio.1; is a good choice. Unlike + <command>tar</command>, + <command>cpio</command> does not know + how to walk the directory tree and it must be provided the list of files + to backup.</para> + + <para>For example, a list of files can be created using + <command>ls</command> or <command>find</command>. This example + creates a recursive listing of the current directory which is + then piped to <command>cpio</command> in order to create an + output backup file named + <filename>/tmp/mybackup.cpio</filename>.</para> + + <example> + <title>Using<command>ls</command> and <command>cpio</command> + to Make a Recursive Backup of the Current Directory</title> + + <screen>&prompt.root; <userinput>ls -R | cpio -ovF /tmp/mybackup.cpio</userinput></screen> + </example> <indexterm> <primary>backup software</primary> @@ -1801,16 +1807,24 @@ cd0: Attempt to query device size failed <indexterm><primary>POSIX</primary></indexterm> <indexterm><primary>IEEE</primary></indexterm> - <para>&man.pax.1; is the IEEE/&posix; answer to - <command>tar</command> and <command>cpio</command>. Over the - years the various versions of <command>tar</command> and - <command>cpio</command> have become slightly incompatible. So - rather than fight it out to fully standardize them, &posix; - created a new archive utility. <command>pax</command> + <para>A backup utility which tries to bridge the features provided by + <command>tar</command> and <command>cpio</command> is &man.pax.1;. Over the + years, the various versions of <command>tar</command> and + <command>cpio</command> became slightly incompatible. &posix; + created <command>pax</command> which attempts to read and write many of the various <command>cpio</command> and <command>tar</command> formats, - plus new formats of its own. Its command set more resembles - <command>cpio</command> than <command>tar</command>.</para> + plus new formats of its own.</para> + + <para>The <command>pax</command> equivalent to the previous + examples would be:</para> + + <example> + <title>Backing Up the Current Directory With + <command>pax</command></title> + + <screen>&prompt.root; <userinput>pax -wf /tmp/mybackup.pax .</userinput></screen> + </example> </sect2> <sect2 xml:id="backups-programs-amanda"> @@ -1929,7 +1943,7 @@ cd0: Attempt to query device size failed Select the correct country, then choose <guimenuitem>Fixit -- Repair mode with CD-ROM/DVD/floppy or start a shell.</guimenuitem> then select - <guimenuitem>CD-ROM/DVD -- Use the live filesystem + <guimenuitem>CD-ROM/DVD -- Use the live file system CD-ROM/DVD</guimenuitem>. <command>restore</command> and the other needed programs are located in <filename>/mnt2/rescue</filename>.</para> @@ -3588,13 +3602,13 @@ Device 1K-blocks Used Av reports 0 bytes of <literal>dirty</literal> extents.</para> - <para>The next step is to create a filesystem on the + <para>The next step is to create a file system on the <filename>/dev/hast/test</filename> GEOM provider and mount it. This must be done on the <literal>primary</literal> node, as <filename>/dev/hast/test</filename> appears only on the <literal>primary</literal> node. Creating - the filesystem can take a few minutes, depending on the size + the file system can take a few minutes, depending on the size of the hard drive:</para> <screen>&prompt.root; <userinput>newfs -U /dev/hast/test</userinput>
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?201401302106.s0UL6KVB034022>