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Friday, August 05, 2011

Optimal Oracle RMAN Backup Command Options

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Just a very short post about an optimal Oracle RMAN backup command run block.
Here's what *I* think provides an optimal backup for a generic setup.

-- Check our existing files are available before we do some obsolete deleting.
crosscheck archivelog all;
crosscheck backup;

-- Delete any obsolete files before we start so that we have max space available.
-- I have "REDUNDANCY 1" set so that I retain the previous backup until the next backup is completed successfully (you need double disk/tape space available for this).
delete noprompt obsolete;

-- Do the DB and ARCH log backups but put each datafile into it's own piece file.
-- I prefer this because should I need only a specific datafile restored and I have to go to tape, I only need to get the piece that's relevant and this piece is only the datafile needed, saving tape restore time.
-- For Oracle 9i remove the 'as compressed backupset' option.
backup as compressed backupset database filesperset 1 plus archivelog filesperset 1;

-- Now only delete archive logs that are in two separate backups.  This is critical.
delete noprompt archivelog all backed up 2 times to disk;

-- Delete the previous night's backup from disk (obviously you need the space to be able to store two backups on disk).
delete noprompt obsolete;

-- Finally, always a good idea to keep a list of datafiles and temp files that existed at the time of the backup.
report schema;

Make sure that you always save the RMAN backup logs.
I've found that they can be very useful during a restore scenario.

As a tip, you can also run a daily job to list what backups are required to restore a database using the "RESTORE DATABASE PREVIEW SUMMARY;" command.

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