Db2 Houskeeping of combination of Snapshot Backups and TSM Backups

At the moment Db2 supports housekeeping of backups by DB configuration parameters rec_his_retent and num_db_backups. These parameters are used by the customer for years for Db2 TSM backups. Both parameters are set to a value of 8 - ensuring more than one week full backups are available. A full backup is taken Monday to Saturday.

Since some time the customer is using Db2 Snapshot backups (with IBM Flash Copy Manager (FCM)) as well. Now, the implemented automatic deletion of full Db2 database backups does not work (like intended) anymore. In theory it could work, if MAX_VERSIONS / MAX_SNAPSHOT_VERSIONS of acs_profile could be set to a value of 8 as well. But this is highly impractical.


Let's consider a very easy example. Snapshot backups are done on weekdays, on Saturdays a TSM Backup. We assume just one Device Class with 5 targets. MAX_VERSIONS is configured to 5 (acs_profile). Intention is to have 5 snapshot backups available.

Example:

Sat 12/30 TSM Backup
Mon 1/01 Snapshot Backup
Tue 1/02 Snapshot Backup
Wed 1/03 Snapshot Backup
Thu 1/04 Snapshot Backup
Fri 1/05 Snapshot Backup
Sat 1/06 TSM Backup
Mon 1/08 Snapshot Backup
Tue 1/09 Snapshot Backup
Wed 1/10 Snapshot Backup
Thu 1/11 Snapshot Backup
Fri 1/12 Snapshot Backup
Sat 1/13 TSM Backup
Mon 1/15 Snapshot Backup


Using a configuration of

REC_HIS_RETENT 8
NUM_DB_BACKUPS 8
and
MAX_VERSIONS 5 (acs_profile)

The first 5 Snapshot backups use the 5 available targets.
Snapshot backup of 1/08 'overwrites' the snapshot of 1/01. This is the 6th snapshot backup, 8th backup.
Snapshot backup of 1/09 'overwrites' the snapshot of 1/02 (7th snapshot, 9th backup).

Now, following the backup, Db2 history is purged, and TSM Backup of 12/30 will be marked expired (and the appropriate logs).
Since the snapshot backups of 1/01 and 1/02 were 'overwritten' (although still in Db2 history) the oldest restore point in time would be 1/03, thus the intended service level of being able to restore the database 8 days backwards will be missed.

As a workaround the customer marks 'overwritten' snapshot backups manually as deleted (D) using UPDATE HISTORY ... to avoid loosing necessary backups.


We would ask if it would be possible to handle the combination of Snapshot- and TSM-Backups (and file system backups) appropriately. Db2 should be able use the configuration of MAX_VERSIONS etc. (acs_profile)

This shouldn't be impossible, because Db2 has all the necessary knowledge, ACS configuration and the backups performed. And using a mixture of filesystem and TSM backups works like expected.


The manual Db2 history updates of snapshot backups works in the current environment, but if more and more Db2 systems will use snapshot backups in the future with changing configuration and infrastructure for snapshot backups the manual correction of the Db2 history is getting more and more complicated and error-prone - nearly impossible.