Oracle 11g on Linux
This is a question post, not a problem. If there is a more appropriate forum to ask these questions, then please accept my apologies and advise.
Note that we are not interested in point-in-time recovery, thus I'm ignoring that in the following.
We are looking at changing our traditional backup policy (A level 0 backup weekly with daily level 1 cumulative backups) to the recommended oracle strategy (copy backup with subsequent incremental backups applied to initial copy). After testing the recommended strategy, we noticed that our current strategy includes backups of archive log files while the recommended strategy apparently does not. In fact, the backups using our current strategy includes archive logs from several days. This spurred a discussion of why archive log files would need to be backed up in the first place. In theory, archive log files (in archivelog mode) capture changes to the database since the last backup. Thus, once the next backup is performed, my understanding is that those archive logs should no longer be needed. In practice, a hot backup occurs over a period of time. Thus, archive logs must be kept that are created between the beginning and end of the backup job. Thus, it does make sense to me that those most recent archive log files should be backed up immediately after the database backup, But I don't understand why any archive log files created before the start of the backup job would need to be backed up. This leads to two questions:
1. Why would archive log file backups persist for days after level 1 backups have captured the latest data changes?
2. Why does the recommended strategy (apparently) not include any archive log files, even those created during the backup job?
Thanks.
Jim Wolfe