1<!--$Id: cache.so,v 10.3 2002/09/26 01:38:32 bostic Exp $--> 2<!--Copyright (c) 1997,2008 Oracle. All rights reserved.--> 3<!--See the file LICENSE for redistribution information.--> 4<html> 5<head> 6<title>Berkeley DB Reference Guide: Disk drive caches</title> 7<meta name="description" content="Berkeley DB: An embedded database programmatic toolkit."> 8<meta name="keywords" content="embedded,database,programmatic,toolkit,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,Java,C,C++"> 9</head> 10<body bgcolor=white> 11<table width="100%"><tr valign=top> 12<td><b><dl><dt>Berkeley DB Reference Guide:<dd>Programmer Notes</dl></b></td> 13<td align=right><a href="../program/ram.html"><img src="../../images/prev.gif" alt="Prev"></a><a href="../toc.html"><img src="../../images/ref.gif" alt="Ref"></a><a href="../program/copy.html"><img src="../../images/next.gif" alt="Next"></a> 14</td></tr></table> 15<p align=center><b>Disk drive caches</b></p> 16<p>Many disk drives contain onboard caches. Some of these drives include 17battery-backup or other functionality that guarantees that all cached 18data will be completely written if the power fails. These drives can 19offer substantial performance improvements over drives without caching 20support. However, some caching drives rely on capacitors or other 21mechanisms that guarantee only that the write of the current sector 22will complete. These drives can endanger your database and potentially 23cause corruption of your data.</p> 24<p>To avoid losing your data, make sure the caching on your disk drives is 25properly configured so the drive will never report that data has been written 26unless the data is guaranteed to be written in the face of a power failure. 27Many times, this means that write-caching on the disk drive must 28be disabled.</p> 29<table width="100%"><tr><td><br></td><td align=right><a href="../program/ram.html"><img src="../../images/prev.gif" alt="Prev"></a><a href="../toc.html"><img src="../../images/ref.gif" alt="Ref"></a><a href="../program/copy.html"><img src="../../images/next.gif" alt="Next"></a> 30</td></tr></table> 31<p><font size=1>Copyright (c) 1996,2008 Oracle. All rights reserved.</font> 32</body> 33</html> 34
