Got a pretty big instance on a one-week backup cycle with an incremental (differential) strategy .. or rather, that's what it was supposed to be. Somehow the daily differentials seem to come out as cumulative!? The size of our instance means that this is a bit of a problem – daily backup window in excess of 3 hours is not acceptable at the end of the week.
Our schedule:
Once every week we do an
backup incremental level 0
as copy tag 'sometag'
skip readonly
database;
and once a day
backup incremental level 1
for recover of copy tag 'sometag'
database plus archivelog;
We've configured block-change-tracking for the database
The problem is, that the result is a cumulative incremental backup, which means an increasing backup-window every day, with a reset in the weekends.
What are we doing wrong?
Thoughts:
- Change Tracking is getting screwed up?
- Strategy incompatible with
image copies?
Best Answer
You are doing a differential incremental backup rather than cumulative, but the syntax
for recover of copy tag 'sometag'
indicates that you plan to incrementally update an image file backup. Phil was on the right tack with the missingRECOVER COPY OF DATABASE WITH TAG 'sometag'
. Since you are not running this each incremental must be able to recover the un-updated tag 'sometag' causing it to grow each day as thoughCUMULATIVE
were specified.See Backup Sets and Image Copies in the Concepts Guide and see Incrementally Updating Backups in the Backup and Recovery User's Guide (11.2). If your intention was to use incrementally updated image copies you will want something more like this:
If you didn't intend to do this, then simply remove the
for recover...
syntax.