What are the major RAC wait events?

The most common wait events related to this are gc cr request and gc buffer busy (note that in Oracle RAC 9i and earlier these wait events were known as “global cache cr request”and “global cache buffer busy” wait events).

What is Gc wait event Oracle RAC?

The gc current block busy wait event indicates that the access to cached data blocks was delayed because they were busy either in the remote or the local cache. This could be caused by any of the following: ■ The blocks were pinned. ■ The blocks were held up by sessions.

What is reliable message wait event?

Reliable Message waits are cryptic by nature. It is a general purpose wait event that tracks many different types of channel communications within the Oracle database. I’ve read some blogs that suggest that this is a benign wait event that can be ignored.

How can I reduce my cluster wait time?

Another way to reduce the SQL statement’s cluster wait time is to execute the query on one node so that no cluster waits are needed. Obviously, this is accomplished with services and application partitioning.

What are the top 5 wait events in Oracle?

Oracle Wait Events and Solution

  • Buffer Busy Wait:
  • Db File Sequential Read :
  • Enq: TX – row lock contention :
  • Enq: TM – index contention :
  • Row Cache Lock Wait :
  • Read by Other Session :

What is Cache Fusion in Oracle RAC?

As the name suggests, CACHE FUSION is the amalgamation of cache from each node/instance participating in the RAC, but it is not any physically secured memory component which can be configured unlike the usual buffer cache (or other SGA components) which is local to each node/instance.

How do I resolve log file sync wait event?

The Oracle “log file sync” wait event is triggered when a user session issues a commit (or a rollback)….If slow I/O, investigate the following:

  1. Reduce contention on existing disks.
  2. Put log files on faster disks.
  3. Put alternate redo logs on different disks to minimize the effect archive processes (log files switches).

What is cluster wait?

Cluster wait events are caused by multiple nodes in the cluster needing access to the same set of data. These must be tracked down on an individual basis. Usually there are multiple statements and tables that have contention problems.

What are the different wait events?

The most common wait events related to this are gc cr request and gc buffer busy. PL/SQL Lock Timer—This wait event represents the amount of time a user or application has “slept” through the USER_LOCK. SLEEP or DBMS_LOCK. SLEEP procedures.

What are the different wait events in Oracle?

What is split brain in RAC?

Split Brain is often used to describe the scenario when two or more nodes in a cluster, lose connectivity with one another but then continue to operate independently of each other, including acquiring logical or physical resources, under the incorrect assumption that the other process(es) are no longer operational or …

What is GES and GCS in Oracle RAC?

The GCS and GES are integrated components of Real Application Clusters that coordinate simultaneous access to the shared database and to shared resources within the database and database cache. GES and GCS together maintain a Global Resource Directory (GRD) to record information about resources and enqueues.