88 lines
5.2 KiB
HTML
88 lines
5.2 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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<meta name="DC.Title" content="Special considerations for journal entries" />
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<meta name="abstract" content="Many journaled integrated file system operations internally use commitment control to form a single transaction from the multiple functions performed during the operations." />
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<meta name="description" content="Many journaled integrated file system operations internally use commitment control to form a single transaction from the multiple functions performed during the operations." />
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<meta name="copyright" content="(C) Copyright IBM Corporation 1999, 2006" />
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<meta name="DC.Identifier" content="rzaaxspecial" />
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<!-- All rights reserved. Licensed Materials Property of IBM -->
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<link rel="stylesheet" type="text/css" href="./ic.css" />
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<title>Special considerations for journal entries</title>
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</head>
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<body id="rzaaxspecial"><a name="rzaaxspecial"><!-- --></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">Special considerations for journal entries</h1>
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<div><p>Many journaled integrated file system operations internally use
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commitment control to form a single transaction from the multiple functions
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performed during the operations.</p>
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<p>These journaled operations should not be considered complete unless the
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commitment control cycle has a Commit journal entry (Journal Code C, Type
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CM). Journaled operations that contain a Rollback journal entry (Journal Code
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C, Type RB) in the commitment control cycle are failed operations, and the
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journal entries within them should not be replayed or replicated.</p>
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<p>Journaled integrated file system entries (Journal Code B) that use commitment
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control in this manner include:</p>
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<ul><li>AA — Change Audit Value</li>
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<li>B0 — Begin Create</li>
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<li>B1 — Create Summary</li>
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<li>B2 — Add link</li>
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<li>B3 — Rename/Move</li>
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<li>B4 — Unlink (Parent Directory)</li>
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<li>B5 — Unlink (Link)</li>
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<li><img src="./delta.gif" alt="Start of change" />B7 — Created object authority information<img src="./deltaend.gif" alt="End of change" /></li>
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<li>FA — Attribute Change</li>
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<li>JT — Start Journal (only when journaling is started because of an operation
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in a directory with the inherit journaling attribute of Yes)</li>
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<li>OA — Authority Change</li>
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<li>OG — Object Primary Group Change</li>
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<li>OO — Object Owner Change</li>
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</ul>
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<p>Several integrated file system journal entries have a specific data field
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indicating whether the entry is a summary entry. Operations that send summary
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entry types will send two of the same entry types to the journal. The first
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entry contains a subset of the entry specific data. The second entry contains
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complete entry specific data and will indicate that it is a summary entry.
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Programs that are replicating the object or replaying the operation will generally
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only be interested in the summary entries.</p>
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<p>For a create operation in a journaled directory, the B1 journal entry (Create
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Summary) is considered the summary entry.</p>
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<p>Some journaled operations need to send a journal entry that is conversely
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related to the operation. For example, a commitment control cycle containing
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a B4 journal entry (Unlink) may also contain a B2 journal entry (Add Link).
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This type of scenario will only occur in operations that result in a Rollback
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journal entry (C — RB) .</p>
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<p>This scenario may occur for two reasons:</p>
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<ol><li>The operation was about to fail, and the entry was needed internally for
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error path cleanup.</li>
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<li>The operation was interrupted by a system outage, and during the subsequent
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IPL, recovery that needed to send the entry was performed to rollback the
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interrupted operation.</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="rzaaxjournaloverview.htm" title="These topics introduce journaling support for integrated file system objects.">Journaling overview</a></div>
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</div>
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<div class="relinfo"><strong>Related information</strong><br />
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<div><a href="../rzaki/rzakifinder.htm">Journal entry information finder</a></div>
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</div>
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</div>
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</body>
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</html>
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