The Oracle Service Layer

Besides monitoring the session load on the cluster service and pinpointing issues in load-balancing across cluster instances, this layer monitors the following:

  • The availability and responsiveness of the cluster service;
  • The number and nature of wait events that occur on each instance of the cluster, and the sessions/session modules affected by these waits;
  • The target and estimated MTTR (Mean Time to Recovery) for every instance;
  • Accesses to the undo tablespace of an instance.


Figure 1 : The Oracle Service Layer