75 lines
4.8 KiB
HTML
75 lines
4.8 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 http-equiv="Content-Type" content="text/html; charset=utf-8" />
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<meta name="security" content="public" />
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<meta name="Robots" content="index,follow" />
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<meta http-equiv="PICS-Label" content='(PICS-1.1 "http://www.icra.org/ratingsv02.html" l gen true r (cz 1 lz 1 nz 1 oz 1 vz 1) "http://www.rsac.org/ratingsv01.html" l gen true r (n 0 s 0 v 0 l 0) "http://www.classify.org/safesurf/" l gen true r (SS~~000 1))' />
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<meta name="DC.Type" content="concept" />
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<meta name="DC.Title" content="How SMAPP works" />
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<meta name="abstract" content="The purpose of system-managed access-path protection (SMAPP) is to reduce the amount of time it takes to restart the system or vary on an independent disk pool, after an abnormal end." />
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<meta name="description" content="The purpose of system-managed access-path protection (SMAPP) is to reduce the amount of time it takes to restart the system or vary on an independent disk pool, after an abnormal end." />
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<meta name="DC.Relation" scheme="URI" content="rzakismappintro.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="rzakihowworks" />
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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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<!-- US Government Users Restricted Rights -->
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<!-- Use, duplication or disclosure restricted by -->
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<!-- GSA ADP Schedule Contract with IBM Corp. -->
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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>How SMAPP works</title>
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</head>
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<body id="rzakihowworks"><a name="rzakihowworks"><!-- --></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">How SMAPP works</h1>
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<div><p>The purpose of system-managed access-path protection (SMAPP) is
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to reduce the amount of time it takes to restart the system or vary on an
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independent disk pool, after an abnormal end.</p>
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<p>It can take much longer than normal to restart the system when the system
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ends abnormally because of something like a power interruption. Also, if you
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are using an independent disk pool, the next vary on of the independent disk
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pool can take much longer than normal.</p>
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<div class="section"><h4 class="sectiontitle">Access paths</h4><p>An <span class="uicontrol">access path</span> describes
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the order in which records in a database file are processed. A file can have
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multiple access paths, if different programs need to see the records in different
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sequences.</p>
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</div>
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<div class="section"><h4 class="sectiontitle">How SMAPP works with abnormal ends</h4><p>When the system
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restarts after an abnormal end, the system rebuilds access paths that were
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open for updating at the time of the abnormal end. Rebuilding access paths
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contributes to this long restart time. Likewise, when you vary on an independent
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disk pool, the system rebuilds access paths that were open for updating at
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the time the independent disk pool ended abnormally. The system does not rebuild
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access paths that are specified as MAINT(*REBLD) when you create them. When
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protecting access paths with SMAPP, the system uses information that it has
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collected to bring access paths up to date, rather than rebuilding them.</p>
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<p>You
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can specify the target time for rebuilding access paths after the system ends
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abnormally. The target time is a goal that the system does its best to achieve.
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The actual recovery time for access paths after a specific failure may be
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somewhat more or less than this target.</p>
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<p>The target recovery time for
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access paths can be specified for the entire system or for individual disk
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pools. The system dynamically selects which access paths to protect to meet
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this target. It periodically estimates how long it will take to recover access
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paths that are open for change.</p>
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<p> For new systems, the system-wide
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recovery time for access paths is 50 minutes, which is the default. If you
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move from a release that does not provide the SMAPP function to a release
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that supports SMAPP, the system-wide recovery time for access paths is also
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set to 50 minutes.</p>
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</div>
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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="rzakismappintro.htm" title="System-managed access-path protection (SMAPP) allows you to use some of the advantages of journaling without explicitly setting up journaling. Use SMAPP to decrease the time it takes to restart your system after an abnormal end.">System-managed access-path protection</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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