Cluster resource management enables you to manage resources for multiple clusters using the same shared storage.

An I/O Resource Management (IORM) cluster plan allocates storage server resources across multiple clusters. Each directive in a cluster plan specifies an allocation to a cluster rather than an individual database or consumer group.

For example, consider a system hosting two clusters, clusterA and clusterB. Now imagine a cluster plan with share-based resource allocation where clusterA has three shares, and clusterB has one share. In that case, and in the absence of any other clusters and IORM plans, the databases running in clusterA share 75% of the I/O resources (3 out of 4 shares), while the databases in clusterB share the remaining 25% (1 out of 4 shares).

Any cluster without an explicit share allocation is allocated one share by default. This includes any cluster not identified in the cluster plan. So, continuing from the previous example, if the system contains two more clusters (clusterC and clusterD), each additional cluster is allocated one share by default. In this case, clusterA now has 3 out of 6 shares, while clusterB, clusterC, and clusterD each have one share.

The cluster plan uses ASM-scoped security for cluster identification. In each cluster plan directive, the value of the name attribute must match the asm field in the cellkey.ora file, which is part of the ASM-scoped security definition for the cluster. If ASM-scoped security is not configured correctly, the cluster cannot be identified and associated with a directive in the cluster plan. In this case, even if it is named in the cluster plan, the cluster is treated the same as an unidentified cluster, receiving one share of IO resources by default.

The cluster plan can work in conjunction with an interdatabase resource plan, but only if the interdatabase resource plan does not use allocation-based resource management (using allocation and level directives). In this case, directives from both plans are applied to determine the share of resources.

So, continuing from the previous example, imagine that the databases in clusterA are in an interdatabase resource plan with share-based resource allocation. In that case, the resources allocated in the cluster plan to clusterA are further divided and shared amongst the databases by using the directives in the interdatabase resource plan.

The cluster plan cannot work in conjunction with a category plan. You cannot set IORM cluster plan directives when category plan directives exist. Likewise, you cannot set category plan directives when cluster plan directives exist.

The cluster plan is configured and enabled on each storage server using the CellCLI ALTER IORMPLAN command.