Oracle RAC Waits Response Test
This test reports the key performance statistics pertaining to the following wait events in each Oracle instance:
- log file parallel write: This event occurs when writing redo records to the redo log files from the log buffer. Writing redo records to the redo log files from the log buffer.
- Db file parallel write: This event occurs in the DBWR. It indicates that the DBWR is performing a parallel write to files and blocks. When the last I/O has gone to disk, the wait ends.
- log file sync: When a user session commits, the session’s redo information needs to be flushed to the redo logfile. The user session will post the LGWR to write the log buffer to the redo log file. When the LGWR has finished writing, it will post the user session.
- Db file sequential read: The session waits while a sequential read from the database is performed. This event is also used for rebuilding the control file, dumping datafile headers, and getting the database file headers.
Effective wait analysis helps determine on which wait event the instance spends most of its time, and which current connections are responsible for the above-mentioned wait events.
Target of the test : Oracle RAC
Agent deploying the test : An internal/remote agent
Outputs of the test : One set of results for every wait event type captured on every instance in the monitored Oracle RAC.
|
Measurement | Description | Measurement Unit | Interpretation |
---|---|---|---|
Total waits: |
Indicates the total number of times this wait event has occurred since the last measurement period. |
Number |
If the value of this measure is very high, then you can drill down further using the detailed diagnosis capability (if enabled) of the eG Enterprise to figure out which current connections may be responsible for this. The detailed diagnosis of this measure reveals the session IDs of the sessions that caused the wait events to occur, the users who initiated the sessions, and the total number of waits, wait time, and the maximum wait time for every session. |
Time waited: |
Indicates the total time for which the events of this type were in existence on this instance. |
Seconds |
Ideally, the value of this measure should be low. |
Average wait time: |
Indicates the average duration of time in which this wait event was persistent since the last measurement period. |
Seconds |
Ideally, the value of this measure should be low. A very high value or a consistent increase in this value is indicative of a problem condition which requires further investigation. Use the detailed diagnosis capability to zoom into the session that has contributed to the abnormal increase in wait time. |