2011-09-13 17:44:24 +00:00
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<title>Disk drive caches</title>
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<link rel="start" href="index.html" title="Berkeley DB Programmer's Reference Guide" />
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<link rel="up" href="program.html" title="Chapter 15. Programmer Notes" />
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<link rel="prev" href="program_ram.html" title="Memory-only or Flash configurations" />
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<div class="libver">
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2012-11-14 21:35:20 +00:00
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<p>Library Version 11.2.5.3</p>
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2011-09-13 17:44:24 +00:00
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</div>
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<table width="100%" summary="Navigation header">
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<tr>
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<th colspan="3" align="center">Disk drive caches</th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="program_ram.html">Prev</a> </td>
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<th width="60%" align="center">Chapter 15.
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Programmer Notes
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</th>
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<h2 class="title" style="clear: both"><a id="program_cache"></a>Disk drive caches</h2>
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</div>
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</div>
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</div>
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<p>Many disk drives contain onboard caches. Some of these drives include
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battery-backup or other functionality that guarantees that all cached
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data will be completely written if the power fails. These drives can
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offer substantial performance improvements over drives without caching
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support. However, some caching drives rely on capacitors or other
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mechanisms that guarantee only that the write of the current sector
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will complete. These drives can endanger your database and potentially
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cause corruption of your data.</p>
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<p>To avoid losing your data, make sure the caching on your disk drives is
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properly configured so the drive will never report that data has been written
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unless the data is guaranteed to be written in the face of a power failure.
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Many times, this means that write-caching on the disk drive must
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be disabled.</p>
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<a accesskey="u" href="program.html">Up</a>
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<tr>
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<td width="40%" align="left" valign="top">Memory-only or Flash configurations </td>
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<td width="20%" align="center">
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<a accesskey="h" href="index.html">Home</a>
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</td>
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<td width="40%" align="right" valign="top"> Copying or moving databases</td>
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</tr>
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</table>
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