121 lines
7.9 KiB
HTML
121 lines
7.9 KiB
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<!DOCTYPE html
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PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<meta name="DC.Title" content="Linux backup and recovery overview" />
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<title>Linux backup
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and recovery overview</title>
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<body id="rzau9linuxbackupoverview"><a name="rzau9linuxbackupoverview"><!-- --></a>
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<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
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<h1 class="topictitle1">Linux backup
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and recovery overview</h1>
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<div><p>This topic discusses Linux<sup>®</sup> backup and recovery.</p>
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<p>Linux-centric backup is inherently file oriented in nature because Linux backup
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utilities operate at a file level. It is very difficult to back up an entire Linux drive
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as a single entity using Linux backup utilities. The only way to save a complete
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copy of a disk volume using Linux is to buy a third-party imaging
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product. These products require special skills to use, and are not supported
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for use with integrated Linux servers. </p>
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<p>It should be noted that when we discuss Linux file-level backup and the applications
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that can be used to perform this task, we are really talking about Linux flat files,
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that is, non-database files. In <span class="keyword">i5/OS™</span>,
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we usually do not draw such a distinction because we use the same backup tools
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to save both database and non-database files. In Linux, however, you would usually back
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up database files using a backup application that is specific to the installed
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database. Therefore, when we discuss file-level backup in this section it
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is in the context of flat, or non-database, files. </p>
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<p>There are other differences between an <span class="keyword">i5/OS</span> and Linux backup.
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When performing an <span class="keyword">i5/OS</span> backup,
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we usually put the partition to restricted state and save objects direct to
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tape. While the data can be compressed, the objects are written sequentially
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on the tape and not saved to a single container (archive in Linux terms).
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When backing up to tape, this is the most logical and efficient way to perform
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a save. In the Linux world, however, a backup usually means saving
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files to a single archive file on disk. The archive file can then either be
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copied to another Linux server in the network for safekeeping, or dumped
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to tape.</p>
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<p>When we discuss backup we usually assume that we are backing up to tape.
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However, we can also back up to disk. Backing up to disk is usually an intermediate
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step before saving to tape in a staged backup. Ultimately we must back up
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to tape, or to disk on another system to guard against a complete loss of
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the primary system. While backup to tape is fairly straightforward, there
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are applications and techniques that can also be used to save data to disk
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on remote systems so that files can be quickly recovered in the event of a
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data loss.</p>
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<p>Although Linux documentation
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might talk about “disaster recovery” backup, we need to draw a distinction
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between the disaster recovery backup capability provided by <span class="keyword">i5/OS</span> for
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an integrated Linux server, and disaster recovery in the context
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of a Linux backup
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application. From the Linux point of view, a disaster recovery backup is
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a backup of all files on a disk volume or volumes versus backing up selected
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files. However, Linux backup applications still save at a file level,
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and you can still restore individual files from a Linux “disaster recovery” backup. In contrast,
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an <span class="keyword">i5/OS</span> storage space
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backup saves a complete image of a Linux drive as a single entity, and you
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cannot directly restore individual files from it. You can restore the storage
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space to a new name and link it to the same server, then copy the needed files
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from it. However, <span class="keyword">i5/OS</span> storage
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space backup is very fast, and can provide additional functions not readily
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available with a Linux "disaster recovery" backup, such as the ability
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to quickly restore a complete copy of the system drive. In the context of
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this information, we regard all Linux backup operations as file-level
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backups.</p>
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<div class="note"><span class="notetitle">Note:</span> When using a Linux backup application you can use either a native iSeries™ tape
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drive or a standalone Linux server-attached tape drive to save and restore Linux files.
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Both <span class="keyword">i5/OS</span> and Linux cannot
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use an iSeries tape
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drive concurrently; it must be allocated or "locked" to one operating system
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or the other.</div>
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<p>Note that the tape drive must be varied off in the hosting <span class="keyword">i5/OS</span> partition.
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Tape devices show up under the /dev directory, for example, /dev/st0 or /dev/st1. </p>
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<p>Using a Linux application
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to perform file-level backups can be difficult to incorporate into an unattended
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backup from the <span class="keyword">i5/OS</span> side.
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This is because Linux cannot share a tape cartridge formatted for use
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by <span class="keyword">i5/OS</span>.</p>
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<div class="note"><span class="notetitle">Note:</span> Tape libraries and automatic cartridge loaders (ACLs) on the supported
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devices list are not supported in random access mode. However, they are supported
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in manual or sequential access mode.</div>
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<p>There are some good reasons why you might want to use an iSeries tape
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drive in preference to an Integrated xSeries<sup>®</sup> Server or xSeries-attached tape
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drive. iSeries tape
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drives tend to be very fast, reliable, robust and high capacity; and it can
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be possible to consolidate a number of tape drives in your organization down
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to one or two iSeries devices.
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If you have multiple integrated Linux servers in the same <span class="keyword">i5/OS</span> partition,
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they can all access the same tape drive (although not at the same time). Therefore,
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you might only need one iSeries tape drive to back up all your Linux servers. </p>
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<p>You can find more information about Linux backup strategies and automating
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the backup process, along with general information about backup and restore,
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at the following Web site: </p>
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<p><a href="http://www.backupcentral.com/" target="_blank">http://www.backupcentral.com/</a> <img src="www.gif" alt="Link outside information center" /></p>
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</div>
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<div>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="rzau9linuxbackup.htm" title="This topic introduces the techniques you can use to perform Linux-centric backup and recovery on an Integrated xSeries Server or Integrated xSeries Adapter running Linux.">Linux-centric backup and recovery</a></div>
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</div>
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</div>
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</body>
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</html>
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