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89 lines
4.1 KiB
HTML
89 lines
4.1 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>Time Synchronization</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="Getting Started with Berkeley DB, Java Edition High Availability Applications" />
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<link rel="up" href="administration.html" title="Chapter 7. Administration" />
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<link rel="prev" href="administration.html" title="Chapter 7. Administration" />
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<link rel="next" href="nodeconfig.html" title="Node Configuration" />
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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 12.2.7.5</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">Time Synchronization</th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="administration.html">Prev</a> </td>
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<th width="60%" align="center">Chapter 7. Administration</th>
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<td width="20%" align="right"> <a accesskey="n" href="nodeconfig.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="admintimesync"></a>Time Synchronization</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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For best results, you are strongly recommended to synchronize the
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clocks on all the machines hosting your production
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replication group. Running a time synchronization daemon like
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<a class="ulink" href="http://www.ntp.org/" target="_top">NTPD</a> is a simple way to
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keep time synchronized across your replication machines. Once the
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clocks are set, they are maintained by ntpd so that they rarely
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stray more than 128ms away from one another.
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</p>
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<p>
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Be aware the JE checks for clock skew between the Master and
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a starting Replica node, when the Replica node performs its
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startup handshake with the Master. (See
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<a class="xref" href="lifecycle.html#lifecycle-nodestartup" title="Replica Startup">Replica Startup</a>
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for information on the startup handshake.) If the clock skew between
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the two nodes is too large, the handshake is aborted and JE
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throws an <a class="ulink" href="../java/com/sleepycat/je/EnvironmentFailureException.html" target="_top">EnvironmentFailureException</a>.
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</p>
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<p>
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Also, well-synchronized clocks are required for a proper
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implementation of a time consistency policy (see
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<a class="xref" href="consistency.html#timeconsistency" title="Time Consistency Policies">Time Consistency Policies</a>).
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It is also required for correct internal booking by JE.
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</p>
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<p>
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Finally, synchronized system clocks make it easier to correlate
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events in the logging output from different nodes in the group.
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</p>
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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="administration.html">Prev</a> </td>
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<td width="20%" align="center">
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<a accesskey="u" href="administration.html">Up</a>
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</td>
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<td width="40%" align="right"> <a accesskey="n" href="nodeconfig.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">Chapter 7. Administration </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"> Node Configuration</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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