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<title>Understanding snapshot views</title>

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<h1> Understanding snapshot backup</h1>
<p>The snapshot function creates a quick backup copy of data. It sets up a link between
the source and target logical devices; then, it creates a backup of the source
data on the target drive. Any changes made to the source drive after you create a snapshot backup
are not reflected on the target drive.
You can use the backup copy of data for tape backup, drive
cloning, and multi-server rollout.</p>
<p>
There are two primary snapshot functions: backup and nobackup. The snapshot
backup function copies the entire contents of the source drive to the target
drive so that entire logical devices can be moved from one server to another. The
snapshot nobackup function creates a temporary copy of a drive for
tape drive backup and reference purposes. The snapshot nobackup function is less
I/O-intensive than the snapshot backup function.</p>
<p>
Before using snapshot, consider the following requirements:</p>
<ul>
<li>You can perform a snapshot backup operation on only one controller at a time.</li>
<li>The source and target logical devices can have the same or different RAID level (they do not have to match).</li>

<li>The source and target logical devices must be on the same controller.</li>
<li>You can create a maximum of four independent snapshot backups per controller.

<li>There is no limit on the size of the source and target logical device. However,
for both snapshot backup and nobackup operations,
the size of the target drive must be greater than or equal to the source drive.</li>

<li>You cannot perform any action on a snapshot source or target logical device (such as verifying the drive). You can only delete a snapshot backup.</li>

</ul>

<h2>More information</h2>

<ul>
  <li><a href="aflash.htm">Creating a snapshot backup</a></li>
  <li><a href="armflash.htm">Removing a snapshot backup</a></li>

</ul>

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