Oracle Rollback Segments Test
Rollback segments are the undo records, which contain the picture before the database changes. These segments are a critical part of the recovery process and are applied during the rollback phase of the recovery process. The Oracle Rollback Segments test measures the load and the efficiency of the rollback segments.
Note:
This test will not report metrics for an Oracle 12c PDB server.
Target of the test : An Oracle server
Agent deploying the test : An internal agent
Outputs of the test : One set of results for every SID monitored.
|
Measurement | Description | Measurement Unit | Interpretation |
---|---|---|---|
Writes: |
Indicates the total number of writes to a specific rollback segment during the last measurement period. |
Number |
This gives you an indication of the load on a specific rollback segment. |
Waits: |
Indicates the number of header waits during the last measurement period. |
Number |
This indicates the number of times the Oracle Server had to wait to acquire a rollback segment. |
Gets: |
Indicates the number of header gets during the last measurement period. |
Number |
This indicates the number of gets that have happened in a specific rollback segment. |
Current hit ratio: |
Indicates the waits to gets ratio during the last measurement period. |
Percentage |
This indicates the efficiency at which the rollback segments have performed during the last monitored interval. Ideally, the Hit Ratio should be >= 99%. |
Overall hit ratio: |
Indicates the waits to gets ratio from the time the instance was started |
Percentage |
Ideally, the Hit Ratio should be >= 99%. If not, consider adding additional rollback segments. Also, check the system undo header, system undo block, undo header, undo block statistics under “Wait Statistics”, for additional information on rollback contention. |