78 lines
4.7 KiB
HTML
78 lines
4.7 KiB
HTML
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<?xml version="1.0" encoding="UTF-8"?>
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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="Examples: Device parity and mirrored protection" />
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<link rel="stylesheet" type="text/css" href="./ic.css" />
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<title>Examples: Device parity and mirrored protection </title>
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</head>
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<body id="hdraspexamples"><a name="hdraspexamples"><!-- --></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">Examples: Device parity and mirrored protection </h1>
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<div><div class="p">The following examples show different options for protecting disk pools.
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They include:<ul><li>Mirrored protection and device parity protection to protect the system
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disk pool</li>
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<li>Mirrored protection in the system disk pool and device parity protection
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in the user disk pools</li>
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<li>Mirrored protection and device parity protection in all disk pools</li>
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</ul>
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</div>
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<div class="section"><h4 class="sectiontitle">Mirrored protection and device parity protection to protect
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the system disk pool</h4><p>Here is an example of a system with a single
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disk pool (auxiliary storage pool) with both mirrored protection and device
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parity protection. <br /><img src="rzaix522.gif" alt="Example of a single disk pool that has mirrored protection and device parity protection" /><br /></p>
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<p>The figure
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shows a single disk pool with twelve disk units. Disk units 9-12 all have
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the same capacity and are protected by device parity protection. Disk units
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1-8 have varying capacities, but each disk unit can be paired with another
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disk unit of the same capacity when mirrored protection is started. After
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mirrored protection is started, the disk units that have been paired together
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are both identified by the same number. Disk units 1 and 2 are now both named
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1, and so forth. The system will fail if more than one disk unit fails for
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RAID 5 or more than two disk units fail for RAID 6. The failed unit can be
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repaired concurrently. If one of the mirrored disk units fails, the system
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continues to run using the operational unit of the mirrored pair.</p>
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</div>
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<div class="section"><h4 class="sectiontitle">Mirrored protection in the system disk pool and device parity
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protection in the user disk pools</h4><p>Consider device parity protection
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if you have mirrored protection in the system disk pool and you are going
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to create basic or independent disk pools. RAID 5 allows for the system to
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tolerate a failure in one of the disk units in a basic or independent disk
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pool. RAID 6 allows for the system to tolerate a failure in two disk units.
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The failure can be repaired while the system continues to run.</p>
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</div>
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<div class="section"><h4 class="sectiontitle">Mirrored protection and device parity protection in all disk
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pools</h4><p>If you have all disk pools (also known as auxiliary storage
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pools) protected with mirrored protection and you want to add units to the
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existing disk pools, consider using device parity protection as well. RAID 5,
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the system can tolerate a failure in one of the disk units with device parity
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protection. RAID 6, the system can tolerate two disk unit failures. The failed
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units can be repaired while the system continues to run. If a failure occurs
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on a disk unit that has mirrored protection, the system continues to run using
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the operational unit of the mirrored pair.</p>
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</div>
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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="rzalyprtctvsdtalss.htm">Plan for disk protection</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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