mirror of
https://github.com/yasuhirokimura/db18
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Yasuhiro KIMURA
135 lines
5.8 KiB
HTML
135 lines
5.8 KiB
HTML
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml">
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
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<title>Log file removal</title>
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<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
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<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
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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="transapp.html" title="Chapter 11. Berkeley DB Transactional Data Store Applications" />
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<link rel="prev" href="transapp_archival.html" title="Database and log file archival" />
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<link rel="next" href="transapp_recovery.html" title="Recovery procedures" />
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</head>
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<body>
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<div xmlns="" class="navheader">
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<div class="libver">
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<p>Library Version 18.1.40</p>
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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">Log file removal</th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="transapp_archival.html">Prev</a> </td>
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<th width="60%" align="center">Chapter 11. Berkeley DB Transactional Data Store Applications </th>
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<td width="20%" align="right"> <a accesskey="n" href="transapp_recovery.html">Next</a></td>
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</tr>
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</table>
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<hr />
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</div>
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<div class="sect1" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h2 class="title" style="clear: both"><a id="transapp_logfile"></a>Log file removal</h2>
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</div>
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</div>
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</div>
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<p>
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The fourth component of the infrastructure, log file
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removal, concerns the ongoing disk consumption of the database
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log files. Depending on the rate at which the application
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writes to the databases and the available disk space, the
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number of log files may increase quickly enough so that disk
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space will be a resource problem. For this reason, you will
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periodically want to remove log files in order to conserve
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disk space. This procedure is distinct from database and log
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file archival for catastrophic recovery, and you cannot remove
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the current log files simply because you have created a
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database snapshot or copied log files to archival
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media.
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</p>
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<p>
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Log files may be removed at any time, as long as:
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</p>
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<div class="itemizedlist">
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<ul type="disc">
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<li>
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the log file is not involved in an active
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transaction.
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</li>
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<li>
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a checkpoint has been written subsequent to the log
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file's creation.
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</li>
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<li>
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the log file is not the only log file in the
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environment.
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</li>
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</ul>
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</div>
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<p>
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Additionally, when Replication Manager is running the log
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file is older than the most out of date active site in the
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replication group.
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</p>
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<p>
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If you are preparing for catastrophic failure, you will want
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to copy the log files to archival media before you remove them
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as described in <a class="xref" href="transapp_archival.html" title="Database and log file archival">Database and log file
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archival</a>.
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</p>
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<p>
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If you are not preparing for catastrophic failure, any one
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of the following methods can be used to remove log
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files:
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</p>
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<div class="orderedlist">
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<ol type="1">
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<li>
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Run the standalone <a href="../api_reference/C/db_archive.html" class="olink">db_archive</a> utility with the <span class="bold"><strong>-d</strong></span> option, to remove any log
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files that are no longer needed at the time the command is
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executed.
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</li>
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<li>
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Call the <a href="../api_reference/C/logarchive.html" class="olink">DB_ENV->log_archive()</a> method from the application,
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with the <a href="../api_reference/C/logarchive.html#archive_DB_ARCH_REMOVE" class="olink">DB_ARCH_REMOVE</a> flag, to remove any log files
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that are no longer needed at the time the call is
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made.
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</li>
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<li>
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Call the <a href="../api_reference/C/envlog_set_config.html" class="olink">DB_ENV->log_set_config()</a> method from the
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application, with the <a href="../api_reference/C/envlog_set_config.html#log_set_config_DB_LOG_AUTO_REMOVE" class="olink">DB_LOG_AUTO_REMOVE</a> flag, to remove
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any log files that are no longer needed on an ongoing
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basis. With this configuration, Berkeley DB will
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automatically remove log files, and the application will
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not have an opportunity to copy the log files to backup
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media.
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</li>
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</ol>
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</div>
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</div>
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<div class="navfooter">
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<hr />
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<table width="100%" summary="Navigation footer">
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<tr>
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<td width="40%" align="left"><a accesskey="p" href="transapp_archival.html">Prev</a> </td>
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<td width="20%" align="center">
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<a accesskey="u" href="transapp.html">Up</a>
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</td>
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<td width="40%" align="right"> <a accesskey="n" href="transapp_recovery.html">Next</a></td>
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</tr>
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<tr>
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<td width="40%" align="left" valign="top">Database and log file
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archival </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"> Recovery procedures</td>
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</tr>
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</table>
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</div>
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</body>
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</html>
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