mirror of
https://github.com/berkeleydb/je.git
synced 2024-11-15 01:46:24 +00:00
84 lines
4.2 KiB
HTML
84 lines
4.2 KiB
HTML
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||
<head>
|
||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||
<title>Time Synchronization</title>
|
||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB, Java Edition High Availability Applications" />
|
||
<link rel="up" href="progoverview.html" title="Chapter 2. Replication API First Steps" />
|
||
<link rel="prev" href="secondary.html" title="Secondary Nodes" />
|
||
<link rel="next" href="two-node.html" title="Configuring Two-Node Groups" />
|
||
</head>
|
||
<body>
|
||
<div xmlns="" class="navheader">
|
||
<div class="libver">
|
||
<p>Library Version 12.2.7.5</p>
|
||
</div>
|
||
<table width="100%" summary="Navigation header">
|
||
<tr>
|
||
<th colspan="3" align="center">Time Synchronization</th>
|
||
</tr>
|
||
<tr>
|
||
<td width="20%" align="left"><a accesskey="p" href="secondary.html">Prev</a> </td>
|
||
<th width="60%" align="center">Chapter 2. Replication API First Steps</th>
|
||
<td width="20%" align="right"> <a accesskey="n" href="two-node.html">Next</a></td>
|
||
</tr>
|
||
</table>
|
||
<hr />
|
||
</div>
|
||
<div class="sect1" lang="en" xml:lang="en">
|
||
<div class="titlepage">
|
||
<div>
|
||
<div>
|
||
<h2 class="title" style="clear: both"><a id="timesync"></a>Time Synchronization</h2>
|
||
</div>
|
||
</div>
|
||
</div>
|
||
<p>
|
||
For best results, you should synchronize the clocks used by all
|
||
machines in a replication group. If you are using a time-based
|
||
consistency policy, this is an absolute requirement
|
||
(see <a class="xref" href="consistency.html#timeconsistency" title="Time Consistency Policies">Time Consistency Policies</a> for more information).
|
||
Time synchronization is easily achieved using a mechanism like <a class="ulink" href="http://www.ntp.org/" target="_top">NTPD</a>.
|
||
</p>
|
||
<p>
|
||
In addition, time synchronization is also a requirement for
|
||
internal JE HA bookkeeping. For example, JE checks for clock
|
||
skew between the Master and a Replica
|
||
when the Replica performs its startup handshake with the
|
||
Master. This handshake will abort and throw
|
||
<a class="ulink" href="../java/com/sleepycat/je/EnvironmentFailureException.html" target="_top">EnvironmentFailureException</a> if the clock skew between the
|
||
two machines is greater than the value set for the
|
||
<a class="ulink" href="../java/com/sleepycat/je/rep/ReplicationConfig.html#MAX_CLOCK_DELTA" target="_top">MAX_CLOCK_DELTA</a> property. This property can be set using the
|
||
<a class="ulink" href="../java/com/sleepycat/je/rep/ReplicationConfig.html#setMaxClockDelta(long, java.util.concurrent.TimeUnit)" target="_top">ReplicationConfig.setMaxClockDelta()</a> method, or in the JE
|
||
configuration file using the
|
||
<code class="literal">je.rep.maxClockDelta</code> property.
|
||
</p>
|
||
<p>
|
||
Finally, well synchronized clocks make it easier to correlate
|
||
events in the logging output from different nodes in the group.
|
||
</p>
|
||
</div>
|
||
<div class="navfooter">
|
||
<hr />
|
||
<table width="100%" summary="Navigation footer">
|
||
<tr>
|
||
<td width="40%" align="left"><a accesskey="p" href="secondary.html">Prev</a> </td>
|
||
<td width="20%" align="center">
|
||
<a accesskey="u" href="progoverview.html">Up</a>
|
||
</td>
|
||
<td width="40%" align="right"> <a accesskey="n" href="two-node.html">Next</a></td>
|
||
</tr>
|
||
<tr>
|
||
<td width="40%" align="left" valign="top">Secondary Nodes </td>
|
||
<td width="20%" align="center">
|
||
<a accesskey="h" href="index.html">Home</a>
|
||
</td>
|
||
<td width="40%" align="right" valign="top"> Configuring Two-Node Groups</td>
|
||
</tr>
|
||
</table>
|
||
</div>
|
||
</body>
|
||
</html>
|