Which archivelogs are required for restoring database

Question

I'm moving to RMAN direct to tape backups (via Netbackup). I'm hoping someone can clarify for me which archivelogs are needed for restoring/recovering a RMAN "hot" backup.
I will have two tape pools with different retention periods:
- standard (kept for 2 months)
- long term (kept for 7 years)
I plan to backup as follows:
- archivelogs every 15 mins direct to the standard pool
- daily backups to the standard pool
- monthend backups to the long term pool
Month ends will either be a full or a full plus a cumulative (level 2) (depending on the weekday that month end falls on).
The bit I'm concerned about is archivelogs. After 2 months they will be expired on tape. But do I need archive logs in order to restore the month end backups?
At the moment I record the SCN before the backup begins and after it finishes (retrieved via select first_change# first_scn from v$log where status = 'CURRENT'). Before recording the post-backup SCN, I force a logfile switch.
For clones, I always restore to the post-backup SCN that I previously recorded (rather than using the tag I associated with the backup).
So a few questions related to restoring after the 2 month window:
- do I need the archivelogs created during the timespan of the backup ran in order to restore to the post-backup SCN?
- If so, is just backing up these archivelogs (to the long term pool) by specifying the range of pre-backup SCN to post-backup SCN sufficient or are additional archivelogs likely to be required?
- if I restore the database and don't specify an SCN but just specify the tag used at the time of the backup, will archive logs be required at all? In this case what would be the state of the restored database - would it be as it was at the beginning or at the end of the backup?

Answer 1

Hi user4835675,
do I need the archivelogs created during the timespan of the backup ran in order to restore to the post-backup SCN?Yes.
If so, is just backing up these archivelogs (to the long term pool) by specifying the range of pre-backup SCN to post-backup SCN sufficient or are additional
archivelogs likely to be required?Can you do a skip of the daily backup schedule duing the monthend backups run and run the "archivelogs every 15 mins" job to the long term pool?
Or temporarily stop the "archivelogs every 15 mins" job during the monthend job and run the monthend backup with the "backup database plus archivelog" clause?
if I restore the database and don't specify an SCN but just specify the tag used at the time of the backup, will archive logs be required at all?Yes, you need archivelogs to recover the datafiles to a consistent state.
In this case what would be the state of the restored database - would it be as it was at the beginning or at the end of the backup?You can only restore to a point in time which past the end of the backup.
Rgds,
Tycho