53 lines
2.9 KiB
HTML
53 lines
2.9 KiB
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 data to a disk unit when its corresponding parity data is on a failed disk unit" />
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<title>Example: Writing data to a disk unit when its corresponding parity
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data is on a failed disk unit</title>
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</head>
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<body id="hdrwrtopsfailex3"><a name="hdrwrtopsfailex3"><!-- --></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 data to a disk unit when its corresponding parity
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data is on a failed disk unit</h1>
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<div><p>The write request from the iSeries™ server detects a disk failure
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for the disk unit that contains the corresponding parity data. The write request
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is to sector 2 on disk unit 4. Parity information for disk unit 4, sector
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2, is on failed disk unit 3. The following actions occur: </p>
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<ol><li>A failure is detected on the disk unit that contains the parity data,
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disk unit 3.</li>
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<li>Calculating parity information is not required because it cannot write
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to parity sector 2 of disk unit 3. Therefore, there is no requirement to read
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the original data and the parity information.</li>
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<li>Data is written to disk unit 4, sector 2. <p>A write operation requires
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only one write operation for the new data. Parity data for parity sector 2
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on disk unit 3 will be rebuilt during synchronization after disk unit 3 is
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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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