An active-passive Essbase cluster consists of two Essbase instances, one on each node that share a common storage for configuration and data. Storage is shared across two computers (for example, using a SAN), which removes the need for the administrator to synchronize storage, as well as the constraint of read-only support (as is the case with Essbase active-active clusters in Provider Services). Essbase uses database tables to ensure that only one agent and its associated servers are active to avoid data corruptions on writes. During installation and configuration, a table is created to hold information on configuration and application data existing in the cluster. Active-passive Essbase clusters do not use any file-system locking (that is, essbase.lck files).
We use the Service Failover functionality available in OPMN to cluster Essbase servers to provide active-passive service failover with write-back capability and API support. Clustering Essbase servers provides the capability to switch over automatically to a passive server when the active server fails, thus ensuring that the Essbase Agent is highly available.