The node that opens the first lock on a resource is nominated to be the master node for this resource. This information is stored at the directory node for the resource. In this scheme, the directory node may not be the master node for a resource. The Integrated DLM optimizes the method of lock mastering to use in each situation. The method of lock mastering has an impact on system performance, during normal runtime activity as well as during instance startup.
Performance is optimized when a resource is mastered locally.
When a resource is mastered remotely, all conflicting accesses to this resource result in a message to the master node for this resource, which results in internode message traffic and impacts system performance. Associated with every resource is a directory node and a master node. The directory node maintains information about the node on which a resource is mastered. The node that masters a resource is the master node for the resource. Each node acts as the directory node for a subset of resources.