5486OpS.fm Draft Document for Review October 18, 2004548 IBM Eserver i5 and iSeries System HandbookCluster Resource Services consists of an open set of APIs that provide clusterfacilities. iSeries application providers and customers use the APIs to enhancetheir application availability and to create, configure, and administer the cluster.Systems are defined into the cluster as cluster nodes. Communication interfaceaddresses are defined to form the cluster node-to-node interconnection links.Resilient resources (objects replicated to one or more nodes) are associated witha Cluster Resource Group (CRG) so they can be managed as a single unit.Two types of CRGs are supported: one for data resilience and one for applicationresilience. Data CRGs provide the control to switch the point of access for a setof data to a backup node that maintains an exact replica of that data. ApplicationCRGs control switching an IP address that represents the application server to abackup node and restart the application in the event of a primary node failure.Cluster Resource Services includes integrated facilities such as heartbeatmonitoring, reliable message delivery, switch-over administration, and distributedactivities. The services are built on a robust cluster topology and messagingfunctions that keep track of each node in the cluster and ensure that all nodeshave consistent information about the state of cluster resources.Heartbeat monitoring ensures that each node is active. When the heartbeat for anode fails, the condition is reported so that the cluster can automatically failoverto the resilient resources on the backup node. System Services for highavailability solutions are enhanced with real-time recording of IFS stream filechanges into journals. Data resiliency applications can use this function toprovide enhanced support for this class of objects.IBM works closely with the cluster middleware business partners to provideeasy-to-use cluster management applications, including Lakeview Technologyand Vision Solutions.iSeries clusters support up to 128 nodes. Any OptiConnect, WAN, and LANconnectivity options can be used to build a cluster, as follows: HSL copper and fiber bus connections are fully supported system features.When used with OptiConnect software, they are attractive connectivitymethods for high-end and mid-range models existing in the same location.IASPs and switched disk work in this environment as of V5R1. ATM provides a high-performance connection to remote systems in thecluster. Ethernet and token-ring LANs are ideal for connecting low-end iSeriesmodels into the cluster.
