Env: NetBackup v7.6.1.1, MSDP, single master/media.
If I have the choice/option of either retention models of:
a) 2/8/0 - keep daily diff for 2 weeks, keep weekly full for 8 weeks, keep no monthly full.
...or:
b) 2/4/3 - keep daily diff for 2 weeks, keep weekly full for 4 weeks, keep monthly full for 3 months.
...thus...
...model a) oldest backup is two months old - and holds 8 daily diffs, and 8 fulls.
...model b) oldest backup is three months old - and holds 8 daily diffs, and 7 fulls.
...then which model would consume more back-end post-de-dupe space, and why?
My thinking is that de-dupe is essentially the difference between the oldest and the newest backups, i.e. all changes in between the two date ranges, and so model b) would have the greatest divergence, i.e. as backup ages it essentially appears to MSDP to become more and more unique, because over a longer period of time the most recent full will appear to be more different, because more writes/changes/updates will have occurred on the backup clients.
Hmm.
Thoughts, suggestions, advice, experience?