51 lines
2.8 KiB
HTML
51 lines
2.8 KiB
HTML
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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="Example: Writing to a failed disk unit" />
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<link rel="stylesheet" type="text/css" href="./ic.css" />
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<title>Example: Writing to a failed disk unit</title>
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</head>
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<body id="hdrwrtopsfailex2"><a name="hdrwrtopsfailex2"><!-- --></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">Example: Writing to a failed disk unit</h1>
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<div><p>A write operation from the iSeries™ server detects that the disk
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unit that is to contain the data has failed. The write operation is to disk
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unit 3, sector 1. The following actions occur: </p>
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<ol><li>The original data is lost on disk unit 3, sector 1, because of the failure.</li>
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<li>The new parity data is calculated by reading disk unit 1, sector 1, and
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disk unit 2, sector 1.</li>
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<li>New parity information is calculated.</li>
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<li>New data cannot be written to sector 1 on disk unit 3 because of the failure.</li>
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<li>New parity information is written to parity sector 1 on disk unit 4. <p>Write
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operations require multiple read operations (n-2 reads, where n is the number
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of disk units) and only one write operation for the new parity information.
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Data from disk unit 3 will be rebuilt during synchronization after disk unit
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3 is replaced.</p>
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</li>
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</ol>
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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="rzalywrtopsfail.htm">Write operations on a failed disk unit</a></div>
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</div>
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</div>
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</body>
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