HP StorageWorks 4000s NAS 4000s and 9000s Administration Guide - Page 202

Cluster Administration Hierarchy of Cluster Resource Components The cluster components are referred to as resources and are placed together in groups. Groups are the basic unit of failover between nodes. Resources do not failover individually, rather they failover with the group in which they are contained. In Figure 116 it is depicted as follows: ■ Physical Disk resources are placed in a group and relate to the basic disk created through the WebUI. It should be noted that when a Physical Disk resource is created through Cluster Administrator a corresponding group should be created for the resource to reside in. Groups are the basic unit of failover on a cluster. ■ File Share resources are placed in a group and relate to the actual directory on the drive on which the share is being created. ■ An IP Address resource is formed in the group and relates to the IP address by which the group's virtual server is identified on the network. ■ A Network Name resource is formed in the group and relates to the name published on the network by which the group is identified. ■ A Virtual Server is a group containing an IP Address resource and a Network Name resource. File share and disk resources assigned to this virtual server group can transition from one node to the other during failover conditions. ■ The Group is owned by one of the nodes of the cluster, but may transition to the other nodes during failover conditions. The diagram illustrates a cluster containing two nodes. Each node has ownership of one group. Contained within each group are singular file shares that are known on the network by the associated Network Name and IP address. In the specific case of Node1, file share Eng1 relates to E:\Eng1. This file share is known on the network as \\Fileserver1\Eng1 with an IP address of 172.18.1.99. E:\Eng1 relates to the actual Basic Disk E: containing a directory Eng1. For cluster resources to function properly, two very important requirements should be adhered to: ■ Dependencies between resources of a group must be established. Dependencies determine the order of startup when a group comes online. In the above case, the following order should be maintained: 1. File Share-dependent on Physical Disk Resource 2. NFS File Share-dependent on Physical Disk Resource and Network Name 3. Network Name-dependent on IP Address Failure to indicate the dependencies of a resource properly may result in the file share attempting to come online prior to the physical disk resource being available, resulting in a failed file share. ■ Groups should have a Network Name resource and an IP Address resource. These resources are used by the network to give each group a virtual name. Without this virtual reference to the group, the only way to address a share that is created as a clustered resource is by node name. Physical node names do not transition during a failover, whereas virtual names do. 202 NAS 4000s and 9000s Administration Guide