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Yasuhiro KIMURA
251 lines
10 KiB
HTML
251 lines
10 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>Ex_rep: a replication example</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="rep.html" title="Chapter 12. Berkeley DB Replication" />
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<link rel="prev" href="rep_faq.html" title="Replication FAQ" />
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<link rel="next" href="rep_ex_comm.html" title="Ex_rep_base: a TCP/IP based communication infrastructure" />
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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">Ex_rep: a replication example</th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="rep_faq.html">Prev</a> </td>
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<th width="60%" align="center">Chapter 12. Berkeley DB Replication </th>
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<td width="20%" align="right"> <a accesskey="n" href="rep_ex_comm.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="rep_ex"></a>Ex_rep: a replication example</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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Ex_rep, found in the <code class="filename">examples/c/ex_rep</code>
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subdirectory of the Berkeley DB distribution, is a simple but
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complete demonstration of a replicated application. The
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application is a mock stock ticker. The master accepts a stock
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symbol and a numerical value as input, and stores this
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information into a replicated database; either master or
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clients can display the contents of the database, given an
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empty input line.
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</p>
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<p>
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There are two versions of the application: ex_rep_mgr uses
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Replication Manager, while ex_rep_base uses the replication
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Base API. This is intended to demonstrate that, while the
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basic function of the application is the same in either case,
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the replication support infrastructure differs
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markedly.
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</p>
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<p>
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The communication infrastructure demonstrated with
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ex_rep_base has the same dependencies on system networking and
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threading support as does the Replication Manager (see the
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<a class="xref" href="rep.html#rep_intro" title="Replication introduction">Replication introduction</a>).
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The Makefile created by the standard UNIX configuration will
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build the ex_rep examples on most platforms. Enter "make
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ex_rep_mgr" and/or "make ex_rep_base" to build them.
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</p>
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<p>
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The synopsis for both programs is as follows:
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</p>
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<code class="literal">ex_rep_xxx <span class="bold"><strong>-h home</strong></span>
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<span class="bold"><strong>-l host:port</strong></span> [<span class="bold"><strong>-MC</strong></span>] [<span class="bold"><strong>-r
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host:port</strong></span>] [<span class="bold"><strong>-R
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host:port</strong></span>] [<span class="bold"><strong>-a
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all|quorum</strong></span>] [<span class="bold"><strong>-b</strong></span>]
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[<span class="bold"><strong>-n
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sites</strong></span>] [<span class="bold"><strong>-p
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priority</strong></span>] [<span class="bold"><strong>-v</strong></span>]</code>
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<p>
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where "ex_rep_xxx" is either "ex_rep_mgr" or "ex_rep_base".
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The only difference is that:
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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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<p>
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specifying <span class="bold"><strong>-M</strong></span> or
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<span class="bold"><strong>-C</strong></span> is optional
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for ex_rep_mgr, but one of these options must be
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specified for ex_rep_base.
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</p>
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</li>
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<li>
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<p>
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The <span class="bold"><strong>-n</strong></span> option is
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not supported supported by ex_rep_mgr. That option
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specifies the number of nodes in the replication
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group. When you use the Replication Manager, this
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number is automatically determined for you.
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</p>
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</li>
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</ul>
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</div>
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<p>
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The options apply to either version of the program except
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where noted. They are as follows:
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</p>
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<div class="variablelist">
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<dl>
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<dt>
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<span class="term">
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<span class="bold"><strong>-h</strong></span>
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</span>
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</dt>
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<dd>
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Specify a home directory for the database
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environment.
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</dd>
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<dt>
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<span class="term">
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<span class="bold"><strong>-l</strong></span>
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</span>
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</dt>
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<dd>
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Listen on local host "host" at port "port" for
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incoming connections.
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</dd>
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<dt>
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<span class="term">
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<span class="bold"><strong>-M</strong></span>
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</span>
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</dt>
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<dd>
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Configure this process as a master.
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</dd>
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<dt>
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<span class="term">
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<span class="bold"><strong>-C</strong></span>
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</span>
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</dt>
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<dd>
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Configure this process as a client.
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</dd>
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<dt>
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<span class="term">
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<span class="bold"><strong>-r</strong></span>
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</span>
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</dt>
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<dd>
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Identifies the helper site used for joining the
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group.
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</dd>
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<dt>
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<span class="term">
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<span class="bold"><strong>-R</strong></span>
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</span>
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</dt>
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<dd>
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Identifies a remote peer to be used for joining
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the group. This peer is used for syncing purposes. See
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<a class="xref" href="rep_mastersync.html#rep_c2c_sync" title="Client-to-client synchronization">Client-to-client synchronization</a> for more
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information.
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</dd>
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<dt>
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<span class="term">
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<span class="bold"><strong>-a</strong></span>
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</span>
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</dt>
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<dd>
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Specify repmgr acknowledgement policy of all or
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quorum. See <a href="../api_reference/C/repmgrset_ack_policy.html" class="olink">DB_ENV->repmgr_set_ack_policy()</a> for more
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information (ex_rep_mgr only.)
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</dd>
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<dt>
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<span class="term">
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<span class="bold"><strong>-b</strong></span>
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</span>
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</dt>
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<dd>
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Indicates that bulk transfer should be used.
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See <a class="xref" href="rep_bulk.html" title="Bulk transfer">Bulk transfer</a> for more information.
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</dd>
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<dt>
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<span class="term">
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<span class="bold"><strong>-n</strong></span>
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</span>
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</dt>
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<dd>
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Specify the total number of sites in the
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replication group (ex_rep_base only).
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</dd>
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<dt>
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<span class="term">
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<span class="bold"><strong>-p</strong></span>
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</span>
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</dt>
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<dd>
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Set the election priority. See <a class="xref" href="rep_elect.html" title="Elections">Elections</a>
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for more information.
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</dd>
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<dt>
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<span class="term">
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<span class="bold"><strong>-v</strong></span>
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</span>
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</dt>
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<dd>
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Indicates that additional informational and
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debugging output should be enabled.
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</dd>
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</dl>
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</div>
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<p>
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A typical ex_rep_mgr session begins with a command such as
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the following, to start a master:
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</p>
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<pre class="programlisting">ex_rep_mgr -M -p 100 -h DIR1 -l localhost:30100</pre>
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<p>
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and several clients:
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</p>
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<pre class="programlisting">ex_rep_mgr -C -p 50 -h DIR2 -l localhost:30101 -r localhost:30100
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ex_rep_mgr -C -p 10 -h DIR3 -l localhost:30102 -r localhost:30100
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ex_rep_mgr -C -p 0 -h DIR4 -l localhost:30103 -r localhost:30100</pre>
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<p>
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In this example, the client with home directory DIR4 can
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never become a master (its priority is 0). Both of the other
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clients can become masters, but the one with home directory
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DIR2 is preferred. Priorities are assigned by the application
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and should reflect the desirability of having particular
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clients take over as master in the case that the master fails.
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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="rep_faq.html">Prev</a> </td>
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||
<td width="20%" align="center">
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<a accesskey="u" href="rep.html">Up</a>
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||
</td>
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||
<td width="40%" align="right"> <a accesskey="n" href="rep_ex_comm.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">Replication FAQ </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"> Ex_rep_base: a TCP/IP based communication infrastructure</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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