Automatic Block Media Recovery on Maximum Performance Mode

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Automatic Block Media Recovery is a cool 11gR2 feature. If the database on which a corruption occurs is associated with a real-time query physical standby database, then the database automatically attempts to perform block media recovery. The primary database searches for good copies of blocks on the standby database and, if found, repairs the blocks with no impact to the query that encountered the corrupt block. Only if the database is unable to repair the corruption is the Oracle physical block corruption message (ORA-1578) displayed.

Oracle Database High Availability Overview11g Release 2 (11.2) guide explains the requirements of this feature as below:

Automatic block repair requires the use of the Oracle Active Data Guard option so that you can open a physical standby database for read-write I/O. Also, note that this feature requires that Oracle Data Guard is running in maximum availability mode and has the LOG_ARCHIVE_DEST_n initialization parameter set to the SYNC redo transport mode

But, in a case we experienced in my company last week, we saw in the primary database alert.log, that the database tried to use ABMR in a Maximum Performance Data Guard configuration. Here is the log:



Thu Jan 26 17:01:17 2012
Starting background process ABMR
Thu Jan 26 17:01:17 2012
ABMR started with pid=203, OS id=661
Automatic block media recovery service is active.
Automatic block media recovery requested for (file# 13, block# 1679953)


So we raised an SR to investigate the case and informed that, only requirement is real-time apply and sync or async transport modes are supported for ABMR. This shows that the documentation i mentioned above is not up to date and if you have an 11gR2 Active Data Guard running with Maximum Performance mode, you're able to get benefit from the "Automatic Block Media Recovery" feature.

2 comments:

Azar Mohamed Shaj said...

Thank you :)

Mohamed Azar.

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