<?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="Resilient devices" /> <meta name="abstract" content="Resilient devices are physical resources, represented by a configuration object, such as a device description, that are accessible from more than one node in a cluster." /> <meta name="description" content="Resilient devices are physical resources, represented by a configuration object, such as a device description, that are accessible from more than one node in a cluster." /> <meta name="DC.Relation" scheme="URI" content="rzaigconceptsresilientresources.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="rzaigconceptsresilientdevices" /> <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>Resilient devices</title> </head> <body id="rzaigconceptsresilientdevices"><a name="rzaigconceptsresilientdevices"><!-- --></a> <!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script> <h1 class="topictitle1">Resilient devices</h1> <div><p><dfn class="term">Resilient devices</dfn> are physical resources, represented by a configuration object, such as a device description, that are accessible from more than one node in a cluster.</p> <p><img src="./delta.gif" alt="Start of change" />In the event of an outage, the point of access for the resource is switched to the first backup node in the cluster resource group recovery domain. Independent disk pools, or independent ASPs are resilient devices that can go offline or come online without impacting the rest of system storage. Additionally you can use geographic mirroring which is a subfunction of cross-site mirroring (XSM) which is part of i5/OS™ Option 41, High Available Switchable Resources. Geographic mirroring is a function that keeps two identical copies of an independent disk pool at two sites to provide high availability and disaster recovery. The copy owned by the primary node is the production copy and the copy owned by a backup node at the other site is the mirror copy. User operations and applications access the independent disk pool on the primary node, the node that owns the production copy. <img src="./deltaend.gif" alt="End of change" /></p> <p>A <dfn class="term">resilient device cluster resource group</dfn> can contain a list of switchable devices. Each device in the list identifies a switchable independent disk pool. The entire collection of devices are switched to the backup node when an outage occurs. Optionally, the devices can also be varied on as part of the switchover/failover process. There are limitations related to the physical configuration associated with the list of switchable devices. See <a href="../rzaly/rzalyoverview.htm">Independent disk pools</a> for more information about how to set up the appropriate configuration for an independent disk pool defined to be resilient.</p> <p>A resilient device CRG is very similar to the other types of CRGs. One difference, the list of switchable devices, was mentioned above. Another difference is that the exit program is optional for a device CRG. If environment or data specific processing is needed, an exit program can be used for the CRG. See the <a href="../apis/clrgcrtcrg.htm"><span class="apiname">Create Cluster Resource Group (QcstCreateClusterResourceGroup)</span> API </a> for additional information about this type of CRG.</p> </div> <div> <div class="familylinks"> <div class="parentlink"><strong>Parent topic:</strong> <a href="rzaigconceptsresilientresources.htm" title="Resilient resources are system resources, such as data, devices and applications, that are highly available if you have used clustering on your systems.">Resilient resources</a></div> </div> </div> </body> </html>