Re: RMAN retention vs. netbackup retention

On Dec 18, 3:47 am, "sm" <mike..._at_gmail.com> wrote:
> We're running RMAN backups of Oracle 9iR2 databases using libobk media
> management libraries to send data to a Netbackup tape library. The
> backups from Netbackup's perspective have a specific retention based on
> what I choose to back it up with:
>
> 15 days for archived redo logs
> 2 weeks for a daily backup
> 6 weeks for a weekly backup
>
> However, RMAN simply has a single RMAN config switch called RETENTION
> PERIOD which i can either set to n days or n copies.. We've decided on
> 90-days (ie. retention period of 90 days), but this doesn't match with
> what Netbackup's retention policy would say. After all, RMAN's
> retention period would keep 90 days worth of records of archive log
> backups, yet only 15 days is available on tape. I may have understood
> it wrong but that's the problem I see in my environment. If I do a:
>
> list backup of archivelog all
>
> .. I'd find 90 days worth of archivelogs. Yet when I do a netbackup
> poll of the rman archive logs, it'll only have 15 days worth.
>
> Does anybody else have this issue, or addressed it somehow?

There are 2 retention policies of note:
1. Recovery Window Backup Retention Policy:

         If you need to recover to a point in time two weeks ago, use this.
Configure retention policy to recovery window of 14 days;

2. Backup Redundancy Backup Retention Policy:

    This keeps x copies of each backup. If you run full backups for 3 days and your redundancy is set to 4, the 4th day's backup will obsolete the 1st days backup. It will not remove it, just obsolete it.

The issue you have is the coordination between physical netbackup and the rman catalog. Is there a mandate that you only retain 15 days worth of archive on tape? Do you vault your netbackups?

Either way, the coordination between netbackup and actual catalog can be maintained by using the "CHANGE...Unavailable". Trying to coordinate each backup type with the retention policy seems like asking for some trouble. What if you need those arch logs and you've deleted them? Keep is simple, keep all backups for 'x' time.

If you really want to fine grain the backups, you can put the KEEP command in the backup script, thus overriding the retention policies. Example:

RMAN> backup database keep until time = 'sysdate + 15' logs;

Starting backup at 19-DEC-06
using channel ORA_DISK_1
using channel ORA_DISK_2
backup will be obsolete on date 03-JAN-07 archived logs required to recover from this backup will expire when this backup expires Received on Tue Dec 19 2006 - 10:48:14 CST