<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html lang="en-us" xml:lang="en-us"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <meta name="security" content="public" /> <meta name="Robots" content="index,follow" /> <meta http-equiv="PICS-Label" content='(PICS-1.1 "http://www.icra.org/ratingsv02.html" l gen true r (cz 1 lz 1 nz 1 oz 1 vz 1) "http://www.rsac.org/ratingsv01.html" l gen true r (n 0 s 0 v 0 l 0) "http://www.classify.org/safesurf/" l gen true r (SS~~000 1))' /> <meta name="DC.Type" content="concept" /> <meta name="DC.Title" content="Example: A four-node cluster" /> <meta name="abstract" content="Use this example to create a more complex cluster that contains four nodes." /> <meta name="description" content="Use this example to create a more complex cluster that contains four nodes." /> <meta name="DC.Relation" scheme="URI" content="rzaigscenarios.htm" /> <meta name="copyright" content="(C) Copyright IBM Corporation 1998, 2006" /> <meta name="DC.Rights.Owner" content="(C) Copyright IBM Corporation 1998, 2006" /> <meta name="DC.Format" content="XHTML" /> <meta name="DC.Identifier" content="rzaigscenariosfournode" /> <meta name="DC.Language" content="en-us" /> <!-- All rights reserved. Licensed Materials Property of IBM --> <!-- US Government Users Restricted Rights --> <!-- Use, duplication or disclosure restricted by --> <!-- GSA ADP Schedule Contract with IBM Corp. --> <link rel="stylesheet" type="text/css" href="./ibmdita.css" /> <link rel="stylesheet" type="text/css" href="./ic.css" /> <title>Example: A four-node cluster</title> </head> <body id="rzaigscenariosfournode"><a name="rzaigscenariosfournode"><!-- --></a> <!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script> <h1 class="topictitle1">Example: A four-node cluster</h1> <div><p>Use this example to create a more complex cluster that contains four nodes.</p> <p>This example configuration provides the following:</p> <ul><li>Two-way replication and failover</li> <li>Three-tier environment</li> <li>Applications and data move independently</li> <li>Backup is used for normal production of different workload</li> </ul> <br /><img src="rzaig504.gif" alt="A four-node cluster featuriing two application CRGs and two data CRGs." /><br /><p>The four-node example shows the additional flexibility that is possible with an iSeries™ cluster. There are two application cluster resource groups (A1 and A2) and two data cluster resource groups (D1 and D2). The data associated with D1 is the critical data for the application associated with A1. The data associated with D2 is the critical data for the application associated with A2. Because this is a three-tier environment, the applications exist on the second tier (Node L2 and Node R2) and the data is separated into the third tier (Node L3 and Node R3).</p> <div class="tablenoborder"><table cellpadding="4" cellspacing="0" summary="" frame="border" border="1" rules="all"><thead align="left"><tr><th valign="top" id="d0e39">Cluster resource group (CRG)</th> <th valign="top" id="d0e41">Primary</th> <th valign="top" id="d0e43">Backup</th> </tr> </thead> <tbody><tr><td valign="top" headers="d0e39 ">Application CRG A1</td> <td valign="top" headers="d0e41 ">L2</td> <td valign="top" headers="d0e43 ">R2</td> </tr> <tr><td valign="top" headers="d0e39 ">Application CRG A2</td> <td valign="top" headers="d0e41 ">R2</td> <td valign="top" headers="d0e43 ">L2</td> </tr> <tr><td valign="top" headers="d0e39 ">Data CRG D1</td> <td valign="top" headers="d0e41 ">R3</td> <td valign="top" headers="d0e43 ">L3</td> </tr> <tr><td valign="top" headers="d0e39 ">Data CRG D2</td> <td valign="top" headers="d0e41 ">L3</td> <td valign="top" headers="d0e43 ">R3</td> </tr> </tbody> </table> </div> <p>This enables mutual take-over capability at both the application and data levels. All four nodes are being used for normal production. They are also being used to back up other systems in the cluster. The two applications and their associated data should always be available in this cluster. The outage of any single node will not disrupt availability. In addition, the simultaneous outage of a node at the application level with a node at the data level will not disrupt availability.</p> <div class="note"><span class="notetitle">Note:</span> In either instance, the cluster is running exposed in that some cluster resources will not be replicated while a node is down. You can resolve this by having more than one backup for any critical cluster resource.</div> </div> <div> <div class="familylinks"> <div class="parentlink"><strong>Parent topic:</strong> <a href="rzaigscenarios.htm" title="Use these examples of typical cluster implementations to understand when, why, and how using clusters can be beneficial.">Examples: Cluster configurations</a></div> </div> </div> </body> </html>