How to Synchronize the Standby When there is a Big gap, and all Required Archived Logs are Lost

This post describes a situation that should not happen, having a standby out of synch and not having the required logs to close the gap.

If it is nice to have a procedure to deal with the situation, it is better to assure that archived logs are backed up on a schedule, and that the backup and cleanup script is automatically run every time a threshold of 20% free space on the archive log destination is reached before the next scheduled cleanup run.

In any case this technique is quite nice as it permit to re-synch the standby without needing to copy over the whole database, but only the blocks that were changed since the last standby SCN.

Full details on this document:

How to Synchronize the Standby When there is a Big gap, and all Required Archived Logs are Lost

Comments:

Solution is really good but requires good knowledge of RMAN. Other option is to rebuild DR from primary site .. One doubt from slide 8/25 What was significance of running SQL> alter database flashback off; SQL> alter database flashback on;

Posted by Atul on January 19, 2009 at 05:22 AM IST #

Atul, Yes, if you feel comfortable with RMAN will help, as different scenarios will behave differently than the example, as have happened to me. Still even without RMAN knowledge if you follow the steps in the document the procedure most probably will work. That is specially relevant when the amount of changes is only a small % of the database size. In this case using this technique will permit closing the gap much faster than copying the whole database over to the standby site. About doing 'alter database flashback off/on', in this example the database was configured for fast start failover, that do require flashback database, so before resynchronizing primary and standby we initalize flashback logs with the 'alter database flashback off/on' commands. Regards, Alejandro

Posted by Alejandro on January 19, 2009 at 06:30 AM IST #

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