55 lines
3.9 KiB
HTML
55 lines
3.9 KiB
HTML
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<?xml version="1.0" encoding="UTF-8"?>
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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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<html lang="en-us" xml:lang="en-us">
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<head>
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<meta name="DC.Type" content="concept" />
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<meta name="DC.Title" content="Directory structure and performance (HPOFS)" />
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<meta name="abstract" content="HPOFS volumes have a dual directory structure to access files. Both a hash and hierarchical structure exist to provide a primary and secondary path to the file data. If the primary directory structure becomes damaged, the secondary path is used." />
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<meta name="description" content="HPOFS volumes have a dual directory structure to access files. Both a hash and hierarchical structure exist to provide a primary and secondary path to the file data. If the primary directory structure becomes damaged, the secondary path is used." />
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<meta name="DC.Relation" scheme="URI" content="rzam4highperfofs.htm" />
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<meta name="copyright" content="(C) Copyright IBM Corporation 2004, 2006" />
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<meta name="DC.Rights.Owner" content="(C) Copyright IBM Corporation 2004, 2006" />
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<meta name="DC.Format" content="XHTML" />
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<meta name="DC.Identifier" content="rzam4hpofsdirstructperf" />
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<meta name="DC.Language" content="en-us" />
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<!-- All rights reserved. Licensed Materials Property of IBM -->
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<link rel="stylesheet" type="text/css" href="./ibmdita.css" />
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<link rel="stylesheet" type="text/css" href="./ic.css" />
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<title>Directory structure and performance (HPOFS)</title>
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</head>
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<body id="rzam4hpofsdirstructperf"><a name="rzam4hpofsdirstructperf"><!-- --></a>
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<img src="./delta.gif" alt="Start of change" /><!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
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<h1 class="topictitle1">Directory structure and performance (HPOFS)</h1>
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<div><p>HPOFS volumes have a dual directory structure to access files.
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Both a hash and hierarchical structure exist to provide a primary and secondary
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path to the file data. If the primary directory structure becomes damaged,
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the secondary path is used.</p>
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<p>The hash directory structure is designed to reduce the amount of media
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I/O required, which improves performance for file access. Because of this
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hash directory structure, directory depth has less effect on performance than
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if the directory were searched hierarchically. For example, if /DIRECTORY1
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contains 1000 files and /DIRECTORY2 contains 100 files, file search times
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for files in /DIRECTORY1 will generally take no longer than file searches
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in /DIRECTORY2. This is because the system performs the searches by using
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the hash structure, not the hierarchical structure. </p>
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<p>Directory depth has less effect on performance for a hash search than for
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a hierarchical search. However, the overall directory depths and total number
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of files on a volume will effect performance. In general, a volume with fewer
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files on it will result in better file performance than a volume with more
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files.</p>
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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="rzam4highperfofs.htm" title="High performance optical file system (HPOFS) is an IBM-developed media format architecture available to use when initializing optical media on the i5/OS.">High Performance Optical File System</a></div>
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</div>
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</div>
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<img src="./deltaend.gif" alt="End of change" /></body>
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</html>
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