196 lines
9.6 KiB
HTML
196 lines
9.6 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<html>
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<meta name="Copyright" content="Copyright (c) 2006 by IBM Corporation">
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<title>Cluster APIs--Introduction</title>
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<!-- -->
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<!-- -->
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<!-- -->
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<!-- Begin Developer Note ========================================== -->
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<!-- NOTE: If you are adding, changing, or removing ANY requirements -->
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<!-- for this API chance are good that the GUI code need to change -->
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<!-- also. The Cluster GUI code is built on top of this API and it -->
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<!-- does a certain amount of explicit and implicit validation -->
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<!-- checking of user data prior to the API call being made. Please -->
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<!-- have the Cluster GUI developer check the -->
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<!--/as400/v5r4m0.guix/cur/cmvc/java.pgm/ugcl.guix/com/ibm/as400/opnav/ugcl/ClGuiActionsManager.java/ClGuiActionsManager.java -->
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<!-- part to determine if any Cluster GUI code changes are needed. -->
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<link rel="stylesheet" type="text/css" href="../rzahg/ic.css">
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</head>
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<body>
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<!--Java sync-link ================================================== -->
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<script type="text/javascript" language="Javascript" src="../rzahg/synch.js">
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</script>
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<a name="Top_Of_Page"></a>
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<h2>Cluster APIs--Introduction</h2>
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<p>An iSeries<SUP>(TM)</SUP> <strong>cluster</strong> is defined as a collection of complete
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systems that work together to provide a single, unified computing capability. A
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cluster is identified by a 10-character name. The cluster is comprised of one
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or more <strong>cluster nodes</strong>. A cluster node is an iSeries system
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that is a member of a cluster. Each cluster node is identified by an
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8-character cluster node identifier that is associated with a set of IP
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addresses representing an iSeries system.</p>
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<p>Cluster communications running over IP provides the communications path
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between cluster services on each node in the cluster. Cluster Resource Services
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requires that the loopback IP address on each node be active. The set of
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cluster nodes that have been configured for the cluster is referred to as the
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<strong>cluster membership list</strong>.</p>
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<p>Whenever communication with a node is lost but node or cluster resource
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services failure cannot be guaranteed, a cluster becomes
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<strong>partitioned</strong>. A cluster may be separated into multiple
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partitions. While partitioned, some cluster operations may be restricted.</p>
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<p>High availability through clustering is accomplished through the
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implementation of <strong>resilient resources</strong>. A resilient resource is
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any system resource supported by clustering that is available on more than one
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node in the cluster. If a node in the cluster that is the primary access point
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for a particular set of resilient resources should fail, another node that is
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defined to be the backup for that set of resources will become the access
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point. The definition of the relationship between the nodes associated with a
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set of resilient resources is found in the cluster resource group (CRG) object.
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Cluster resource groups are distributed and coordinated across the nodes in the
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cluster. Cluster resource groups contain a <a href=
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"clust3a1TOC.htm#header_2">recovery domain</a>.</p>
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<p><img src="delta.gif" alt="Start of change"><strong>
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Cluster Administrative Domain</strong> will allow a cluster administrator to maintain a
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consistent operational environment across the cluster or a subset of the cluster.
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<img src="deltaend.gif" alt="End of change"></P>
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<br>
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<h3><a name="Header_3">Example Source Code</a></h3>
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<p>Example control language command source has been provided in the base
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operating system option 7 (Example Tools Library, QUSRTOOL). These commands
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interface to the Cluster Resource Services APIs. See member, TCSTINFO, in file
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QUSRTOOL/QATTINFO for more information.
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<img src="delta.gif" alt="Start of change"> i5/OS<SUP>(R)</SUP> supported CL
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commands can be found by doing "GO CMDCLU" from the command entry screen.
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<img src="deltaend.gif" alt="End of change"></p>
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<p>In addition, example application cluster resource group exit program source
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code can be found in the TCSTAPPEXT and TCSTDTAARA members in file
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QUSRTOOL/QATTSYSC.</p>
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<p>Sample program source has been included which will create the QCSTHAAPPI,
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QCSTHAAPPO data areas and the QACSTOSDS object specifier file. See member
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TCSTDTAEXT in QUSRTOOL/QATTSYSC for the source. This is not a complete program
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as written. Data specific to the application must be added since each
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application has different resiliency requirements.
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<img src="delta.gif" alt="Start of change">See
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<a href="http://www.as400.ibm.com/ha/" target="_blank">High Availability
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and Clusters</a><img src="www.gif" alt="Link outside Information Center"> for
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information on making applications highly available and cluster-proven
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applications. This website also contains more information on QCSTHAAPI data
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area, QCSTHAAPPO data area, and QACSTOSDS object specifier file.
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<img src="deltaend.gif" alt="End of change"></p>
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<br>
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<h3><a name="Header_31">Terminology</a></h3>
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<p><strong>Access point.</strong><img src="delta.gif" alt="Start of change"> For primary-backup
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model,<img src="deltaend.gif" alt="End of change"> the primary point of access for
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a resilient
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resource. If that resource fails, one of the backup resources will become the
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primary access point.
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<img src="delta.gif" alt="Start of change">
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For peer model, the point of access for a resource. All nodes of type peer, are a
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point of access for the resource. <img src="deltaend.gif" alt="End of change">
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</p>
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<p><strong><img src="delta.gif" alt="Start of change">
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Administrative domain.</strong> Monitors and synchronizes changes to selected resources within a cluster. Cluster administrative domain provides easier management and synchronization of attributes for resources that are shared within a cluster, such as environment variable or user profiles.
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</p>
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<p><strong>
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Application
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<img src="deltaend.gif" alt="End of change">takeover IP address.</strong> A floating address that is to be
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associated with an application.</p>
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<p><strong>Clustered hash table.</strong> Non-persistent data that can be
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shared and replicated between cluster nodes using the <a href=
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"clust4a1TOC.htm">Clustered Hash Table APIs</a>.</p>
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<p><strong>Cluster resource group exit program.</strong> A program which
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handles action codes that are passed to it.</p>
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<p><strong>Cluster resource.</strong> A resource that is available on more than
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one cluster node.</p>
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<p><strong>Cluster resource group.</strong> A grouping of cluster resources.
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The group describes a recovery domain and supplies the name of the cluster
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resource group exit program that manages the movement of an access point.</p>
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<p><strong>Device domain.</strong> A subset of nodes in a cluster grouped
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together to share physical hardware resources or the logical resources
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associated with the physical hardware.</p>
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<p><strong>Partition.</strong> Happens when you lose contact between one or
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more nodes in the cluster and a failure of lost nodes cannot be confirmed.</p>
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<p><strong><img src="delta.gif" alt="Start of change">
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Peer model.</strong> Cluster resource groups of this model define nodes
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in the recovery domain with a specific role of either peer or replicate. The peer
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nodes are available to be the access point for the cluster resource groupbut .<img src="deltaend.gif" alt="End of change"></p>
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<p><strong><img src="delta.gif" alt="Start of change">
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Primary-backup model.</strong> Cluster resource groups of this model define nodes
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in the recovery domain with a specific role of either primary, backup or replicate.
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The primary and backup nodes are available to be the access point for the cluster resource group.
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<img src="deltaend.gif" alt="End of change"></p>
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<p><strong>Recovery domain.</strong> A subset of nodes in a cluster grouped
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together to provide availability for one or more resources. A domain represents
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the nodes of the cluster where a cluster resource exists. See <a href=
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"clust3a1TOC.htm">Cluster Resource Groups APIs</a> for more information.</p>
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<p><strong>Resilient resource.</strong> Resources that are recoverable by
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Cluster Resource Services. Three types of system resources that can be
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resilient are (1) objects being replicated between nodes, (2) applications
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using a
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<img src="delta.gif" alt="Start of change">takeover
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<img src="deltaend.gif" alt="End of change">IP address, which can be
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switched from one node to another, and (3)
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hardware devices which can be switched from one node to another.</p>
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<p><strong>Server takeover IP address.</strong> A takeover IP address for
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servers associated with the relational database name in the device description
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for an auxiliary storage pool.</p>
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<p><strong>Singleton cluster.</strong> A one node cluster or a cluster with
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only one active node.</p>
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<hr>
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<center>
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<table cellpadding="2" cellspacing="2">
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<tr align="center">
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<td valign="middle" align="center"><a href="#Top_Of_Page">Top</a> | <a href=
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"clust1.htm">Cluster APIs</a> | <a href="aplist.htm">APIs by category</a></td>
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</tr>
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</table>
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</center>
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</body>
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</html>
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