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Best Practices for Oracle 11g Backup and Recovery using RMAN and Dell EqualLogic Snapshots
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6.3 Point-in-time recovery using FLASHBACK DATABASE and EqualLogic
snapshots – test results
In this section we compare recovery times using Oracle FLASHBACK DATABASE utility and EqualLogic
snapshot based approaches.
The amount of time taken to recover a database using the FLASHBACK DATABASE feature is
proportional to how far back the database needs to be rolled back. Usually this is less than the time
necessary to restore and recover an entire database using RMAN. As shown in Figure 9, it took 63
minutes to recover the database using flashback by two hours, and 90 minutes to recovery it by four
hours.
Figure 9 – Point in time recovery comparison
The test results clearly demonstrate that the amount of time taken to perform point-in-time recovery
primarily depends on the amount of database transactions that have occurred from the point of
recovery up until the current time.
Figure 9 also shows that the time taken to restore the database from an EqualLogic snapshot (using
the procedure outlined in Section 6.2) remains the same regardless of whether the snapshot occurred
two hours back or four hours back in time. This result illustrates a key advantage in using EqualLogic
based snapshots vs. Oracle FLASHBACK DATABASE: you can meet much shorter RTO objectives using
EqualLogic based snapshots.