Oracle rac wait events

The gc current block busy and gc cr block busy events indicate that the remote instance received. The most common wait events related to this are gc cr request and gc buffer busy. For instance, take this comparison.

There are several RAC wait events that are unique to RAC. On a typical single node server , the block is requested by a process, pinning the buffer and thus modifying the block. Monitoring Performance by Analyzing GCS and GES Statistics.

Thus, the chances of catching this event are very low. The foreground process only yields the CPU and will usually be placed at the end of the CPU run queue. Oracle RAC Statistics and Events in AWR and Statspack Reports. Instances and are waiting on the block busy wait event. Many of these wait events are tied to the internal implementation of Oracle and therefore are subject to change or deletion without notice.

Instance is still waiting on the block busy wait event. Application developers should be aware of this and write their code to tolerate missing or extra wait events. The following SQL statement displays an alphabetical list.

You can see Scheduler wait event in Performance page of Oracle Enterprise Manager Cloud Control 13c. Wait events are useful for understanding the bottlenecks. All single instance wait events are applicable to RAC.

Caused may be because of not enough memory on your nodes, overloaded interconnect. Additional Wait Events of Concern. The duration of the wait should be short, and the completion of the wait is most likely followed by a read from disk.

Oracle may not pick private interconnect and instead route traffic over slower public network. RAC event similar to buffer busy waits, tune SQL to request less data, tune network latency between RAC nodes, localize data access. Lost blocks due to Interconnect or CPU. Indicates interconnect issues and contention. When node wants a buffer, it sends a message to the other instance.

This necessitates a disk read. The message is sent to the LMS (Lock Management Server) of the other instance. LMS then sends the buffer to the other instance.

In the above example, it is clear that this system is waiting on CPU, with of the processing time being spent in the CPU. As a general rule, a server is CPU-bound when the number of processes in the execution queue exceeds the number of CPUs on the server. Whenever there’s a systemic issue (like extremely slow log file writes) this query will give good hint towards the cause of problem.

Transferring of blocks from one node to another node is depending on cluster Interconnect.

The client can maintain a dependency for a long time (no other client can change the object). High wait times for this wait event often are because of RAC interconnect Traffic Using Slow Connection or Inefficient Queries. Poorly tuned queries will increase the amount of data blocks requested by an Oracle session. A cursor wait is associated with parsing in some form.

A session may wait for this event when it is trying to get a mutex pin in Share mode but another session is holding the mutex pin on the same cursor object in exclusive. As you can see here, the main wait event to tackle is local write wait.