Re: Determining the no. of arch. redolog files to keep

If you do an offline backup after a clean shutdown, then no archive redo logs present at the time of the backup need keeping (unless, of course, you want to be able to roll forward from an older backup). You will be able to roll forward from the backup using only archive logs written after the subsequent startup.

It is safe to delete archive redo logs while Oracle is running provided you don't delete one currently being written. Each thread may be writing at most one archive log (normally none are being written). Oracle certainly won't be writing an archive log if a shutdown/startup has occured since it was created (they are write-once objects).

I suspect that the manual doesn't mention the offline backup case because it is so simple. Online backup is harder, because the logs written during the backup are essential to any recovery. In the offline case there aren't any of these!

Indeed, if you use offline backup every night, and don't mind loosing one days work, you don't need archive log mode. Received on Tue Sep 21 1993 - 19:12:14 CEST