57 lines
3.4 KiB
HTML
57 lines
3.4 KiB
HTML
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<title>Write operations on a failed disk unit</title>
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<body id="hdrwrtopsfail"><a name="hdrwrtopsfail"><!-- --></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">Write operations on a failed disk unit</h1>
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<div><div class="fignone"><span class="figcap">Figure 1. Device parity set with failed disk unit.</span><p>Some examples show what happens to write operations when a single disk
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unit fails in a device parity set with device parity protection. The following
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figure shows a failed unit under an IOA with device parity protection.</p>
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<p>It shows a parity set with four disk units. Each section of the disk unit
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is marked with a number. Parity sectors are noted with a <em>p</em>. Disk unit
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3 is failed. Disk unit 1 shows sectors 1, 2, 3, and 4p. Disk unit 2 shows
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sectors 4, 1, 2, and 3p. Failed disk unit 3 shows sectors 3, 4, 1, and 2p.
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Disk unit 4 shows sectors 2, 3, 4, and 1p.</p>
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<br /><img src="rzaix508.gif" alt="Figure showing a failed unit in a parity set" /><br /></div>
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<div class="note"><span class="notetitle">Note:</span> RAID 6 operations are derived from RAID 5, but at a further
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level of complexity. Because the concept is similar to RAID 5, RAID 6 operations
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are not described here.</div>
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</div>
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<div>
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<ul class="ullinks">
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<li class="ulchildlink"><strong><a href="rzalywrtopsfailex2.htm">Example: Writing to a failed disk unit</a></strong><br />
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</li>
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<li class="ulchildlink"><strong><a href="rzalywrtopsfailex3.htm">Example: Writing data to a disk unit when its corresponding parity data is on a failed disk unit</a></strong><br />
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</li>
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</ul>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="rzalydppprf.htm">How device parity protection affects performance</a></div>
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