The Oracle software performs the necessary actions without using
scripts; the required steps are an integral part of Real Application Clusters software.
The phases of Real Application Clusters recovery are the following:
Cluster reorganization
When an instance failure occurs, Real Application Clusters must first determine
which nodes of the cluster remain in service. Oracle9i introduced a disk-based
heartbeat in which each database group member votes on what members are
part of the current group. Based on arbitration, a correct current group configuration
is established. The time required for this operation is very brief.
Lock database rebuild
The lock database, which contains the information used to coordinate Real
Application Clusters traffic, is distributed across the multiple active instances.
Therefore, a portion of that information is lost when a node fails. The remaining
nodes have sufficient redundant data to reconstruct the lost information. Once
the cluster membership is determined, the surviving instances reconstruct the
lock database.
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