| <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> |
| <html> |
| <head> |
| <META http-equiv="Content-Type" content="text/html; charset=UTF-8"> |
| <meta content="Apache Forrest" name="Generator"> |
| <meta name="Forrest-version" content="0.9"> |
| <meta name="Forrest-skin-name" content="pelt"> |
| <title>Introduction to hierarchical quorums</title> |
| <link type="text/css" href="skin/basic.css" rel="stylesheet"> |
| <link media="screen" type="text/css" href="skin/screen.css" rel="stylesheet"> |
| <link media="print" type="text/css" href="skin/print.css" rel="stylesheet"> |
| <link type="text/css" href="skin/profile.css" rel="stylesheet"> |
| <script src="skin/getBlank.js" language="javascript" type="text/javascript"></script><script src="skin/getMenu.js" language="javascript" type="text/javascript"></script><script src="skin/fontsize.js" language="javascript" type="text/javascript"></script> |
| <link rel="shortcut icon" href="images/favicon.ico"> |
| </head> |
| <body onload="init()"> |
| <script type="text/javascript">ndeSetTextSize();</script> |
| <div id="top"> |
| <!--+ |
| |breadtrail |
| +--> |
| <div class="breadtrail"> |
| <a href="http://www.apache.org/">Apache</a> > <a href="http://hadoop.apache.org/">Hadoop</a> > <a href="http://hadoop.apache.org/zookeeper/">ZooKeeper</a><script src="skin/breadcrumbs.js" language="JavaScript" type="text/javascript"></script> |
| </div> |
| <!--+ |
| |header |
| +--> |
| <div class="header"> |
| <!--+ |
| |start group logo |
| +--> |
| <div class="grouplogo"> |
| <a href="http://hadoop.apache.org/"><img class="logoImage" alt="Hadoop" src="images/hadoop-logo.jpg" title="Apache Hadoop"></a> |
| </div> |
| <!--+ |
| |end group logo |
| +--> |
| <!--+ |
| |start Project Logo |
| +--> |
| <div class="projectlogo"> |
| <a href="http://hadoop.apache.org/zookeeper/"><img class="logoImage" alt="ZooKeeper" src="images/zookeeper_small.gif" title="ZooKeeper: distributed coordination"></a> |
| </div> |
| <!--+ |
| |end Project Logo |
| +--> |
| <!--+ |
| |start Search |
| +--> |
| <div class="searchbox"> |
| <form action="http://www.google.com/search" method="get" class="roundtopsmall"> |
| <input value="hadoop.apache.org" name="sitesearch" type="hidden"><input onFocus="getBlank (this, 'Search the site with google');" size="25" name="q" id="query" type="text" value="Search the site with google"> |
| <input name="Search" value="Search" type="submit"> |
| </form> |
| </div> |
| <!--+ |
| |end search |
| +--> |
| <!--+ |
| |start Tabs |
| +--> |
| <ul id="tabs"> |
| <li> |
| <a class="unselected" href="http://hadoop.apache.org/zookeeper/">Project</a> |
| </li> |
| <li> |
| <a class="unselected" href="http://wiki.apache.org/hadoop/ZooKeeper">Wiki</a> |
| </li> |
| <li class="current"> |
| <a class="selected" href="index.html">ZooKeeper 3.3 Documentation</a> |
| </li> |
| </ul> |
| <!--+ |
| |end Tabs |
| +--> |
| </div> |
| </div> |
| <div id="main"> |
| <div id="publishedStrip"> |
| <!--+ |
| |start Subtabs |
| +--> |
| <div id="level2tabs"></div> |
| <!--+ |
| |end Endtabs |
| +--> |
| <script type="text/javascript"><!-- |
| document.write("Last Published: " + document.lastModified); |
| // --></script> |
| </div> |
| <!--+ |
| |breadtrail |
| +--> |
| <div class="breadtrail"> |
| |
| |
| </div> |
| <!--+ |
| |start Menu, mainarea |
| +--> |
| <!--+ |
| |start Menu |
| +--> |
| <div id="menu"> |
| <div onclick="SwitchMenu('menu_1.1', 'skin/')" id="menu_1.1Title" class="menutitle">Overview</div> |
| <div id="menu_1.1" class="menuitemgroup"> |
| <div class="menuitem"> |
| <a href="index.html">Welcome</a> |
| </div> |
| <div class="menuitem"> |
| <a href="zookeeperOver.html">Overview</a> |
| </div> |
| <div class="menuitem"> |
| <a href="zookeeperStarted.html">Getting Started</a> |
| </div> |
| <div class="menuitem"> |
| <a href="releasenotes.html">Release Notes</a> |
| </div> |
| </div> |
| <div onclick="SwitchMenu('menu_1.2', 'skin/')" id="menu_1.2Title" class="menutitle">Developer</div> |
| <div id="menu_1.2" class="menuitemgroup"> |
| <div class="menuitem"> |
| <a href="api/index.html">API Docs</a> |
| </div> |
| <div class="menuitem"> |
| <a href="zookeeperProgrammers.html">Programmer's Guide</a> |
| </div> |
| <div class="menuitem"> |
| <a href="javaExample.html">Java Example</a> |
| </div> |
| <div class="menuitem"> |
| <a href="zookeeperTutorial.html">Barrier and Queue Tutorial</a> |
| </div> |
| <div class="menuitem"> |
| <a href="recipes.html">Recipes</a> |
| </div> |
| </div> |
| <div onclick="SwitchMenu('menu_1.3', 'skin/')" id="menu_1.3Title" class="menutitle">BookKeeper</div> |
| <div id="menu_1.3" class="menuitemgroup"> |
| <div class="menuitem"> |
| <a href="bookkeeperStarted.html">Getting started</a> |
| </div> |
| <div class="menuitem"> |
| <a href="bookkeeperOverview.html">Overview</a> |
| </div> |
| <div class="menuitem"> |
| <a href="bookkeeperConfig.html">Setup guide</a> |
| </div> |
| <div class="menuitem"> |
| <a href="bookkeeperProgrammer.html">Programmer's guide</a> |
| </div> |
| </div> |
| <div onclick="SwitchMenu('menu_1.4', 'skin/')" id="menu_1.4Title" class="menutitle">Admin & Ops</div> |
| <div id="menu_1.4" class="menuitemgroup"> |
| <div class="menuitem"> |
| <a href="zookeeperAdmin.html">Administrator's Guide</a> |
| </div> |
| <div class="menuitem"> |
| <a href="zookeeperQuotas.html">Quota Guide</a> |
| </div> |
| <div class="menuitem"> |
| <a href="zookeeperJMX.html">JMX</a> |
| </div> |
| <div class="menuitem"> |
| <a href="zookeeperObservers.html">Observers Guide</a> |
| </div> |
| </div> |
| <div onclick="SwitchMenu('menu_1.5', 'skin/')" id="menu_1.5Title" class="menutitle">Contributor</div> |
| <div id="menu_1.5" class="menuitemgroup"> |
| <div class="menuitem"> |
| <a href="zookeeperInternals.html">ZooKeeper Internals</a> |
| </div> |
| </div> |
| <div onclick="SwitchMenu('menu_1.6', 'skin/')" id="menu_1.6Title" class="menutitle">Miscellaneous</div> |
| <div id="menu_1.6" class="menuitemgroup"> |
| <div class="menuitem"> |
| <a href="http://wiki.apache.org/hadoop/ZooKeeper">Wiki</a> |
| </div> |
| <div class="menuitem"> |
| <a href="http://wiki.apache.org/hadoop/ZooKeeper/FAQ">FAQ</a> |
| </div> |
| <div class="menuitem"> |
| <a href="http://hadoop.apache.org/zookeeper/mailing_lists.html">Mailing Lists</a> |
| </div> |
| </div> |
| <div id="credit"></div> |
| <div id="roundbottom"> |
| <img style="display: none" class="corner" height="15" width="15" alt="" src="skin/images/rc-b-l-15-1body-2menu-3menu.png"></div> |
| <!--+ |
| |alternative credits |
| +--> |
| <div id="credit2"></div> |
| </div> |
| <!--+ |
| |end Menu |
| +--> |
| <!--+ |
| |start content |
| +--> |
| <div id="content"> |
| <div title="Portable Document Format" class="pdflink"> |
| <a class="dida" href="zookeeperHierarchicalQuorums.pdf"><img alt="PDF -icon" src="skin/images/pdfdoc.gif" class="skin"><br> |
| PDF</a> |
| </div> |
| <h1>Introduction to hierarchical quorums</h1> |
| <div id="front-matter"></div> |
| |
| |
| |
| |
| |
| <p> |
| This document gives an example of how to use hierarchical quorums. The basic idea is |
| very simple. First, we split servers into groups, and add a line for each group listing |
| the servers that form this group. Next we have to assign a weight to each server. |
| </p> |
| |
| |
| <p> |
| The following example shows how to configure a system with three groups of three servers |
| each, and we assign a weight of 1 to each server: |
| </p> |
| |
| |
| <pre class="code"> |
| group.1=1:2:3 |
| group.2=4:5:6 |
| group.3=7:8:9 |
| |
| weight.1=1 |
| weight.2=1 |
| weight.3=1 |
| weight.4=1 |
| weight.5=1 |
| weight.6=1 |
| weight.7=1 |
| weight.8=1 |
| weight.9=1 |
| </pre> |
| |
| |
| <p> |
| When running the system, we are able to form a quorum once we have a majority of votes from |
| a majority of non-zero-weight groups. Groups that have zero weight are discarded and not |
| considered when forming quorums. Looking at the example, we are able to form a quorum once |
| we have votes from at least two servers from each of two different groups. |
| </p> |
| |
| <p align="right"> |
| <font size="-2"></font> |
| </p> |
| </div> |
| <!--+ |
| |end content |
| +--> |
| <div class="clearboth"> </div> |
| </div> |
| <div id="footer"> |
| <!--+ |
| |start bottomstrip |
| +--> |
| <div class="lastmodified"> |
| <script type="text/javascript"><!-- |
| document.write("Last Published: " + document.lastModified); |
| // --></script> |
| </div> |
| <div class="copyright"> |
| Copyright © |
| 2008-2013 <a href="http://www.apache.org/licenses/">The Apache Software Foundation.</a> |
| </div> |
| <!--+ |
| |end bottomstrip |
| +--> |
| </div> |
| </body> |
| </html> |
