Can someone explain to me why the following note appears in the sysadmin guide
Note NetBackup recommends that you do not combine differential incremental backups and cumulative incremental backups within the same Windows policy when the incremental backups are based on archive bit (default).
We are starting to take on various flavours of windows clients and I had planned to set up the policies in the same way as our *nix policies. ie FULL, CINC + DIFF in the same policy.
Not really a windows bod so some help would be appreciated. Our Windows bods cant shed any light on this !!
This has more to do with how the OS and Netbackup manage the archive bit markings on the files when it backs them up. Windows and Unix have slightly different methods for determining what is needed to backup during an incremental. This is documented in the Windows Netbackup Administrators Guide I, page 343. The problem occurs when a differential incremental kicks off before a cumulative incremental. The differential incremental will clear all of the archive bits (or timestamps for windows), When the cumulative kicks off, it will not see the bits (or time stamps) and won't backup the files. Therefore you will not have a true cumulative incremental.
It really is not a good idea to have a cumulative and differential incremental in the same policy that is scheduled to run concurrently at any time between Full's.
FULL: backup all files, and clear archive bit CINC: backup files with archive bit, and never clear it DIFF: backup files with archive bit, and clear it
Though if you run like "FULL, DIFF, DIFF, CINC", what happens?
...Yes, if you set retention correctly, no problem. But you may be frightened by small CINC size. :p
Ok, In the windows world what is the point of a cumulative incremental in that case.
You will not be able to recover from the last FULL and the last CINC and have all the changed files in between. (Unless as below DIFF retention is longgggg)
We planned to do .....
SAT1 - FULL (12 months retention) OFFSITE SET1 SUN1 - FULL (12 months retention) OFFSITE SET2 MON-FRI DIFF (14 days) SAT2-4 CINC (1 month) SUN2-4 CINC (1 month)
then round to SAT1 / SUN1 again
This is obviously wrong now I know how windows works !!
How then do you guys set up your windows backups.
Do you have long enough DIFFS to last between your FULLS ?
Why bother with a CINC ?
All backups are duped for offfsite.
Cheers - Darren (Happy with Unix, worried about windows ;-})
> In the windows world what is the point of a cumulative incremental
Restore will only need the last full and the last cumulative images. Some people do weekly fulls and daily cumulatives which uses a little less resources than daily fulls.
with archive bit...Don't mix differential and cumulative in the same policy.Message was edited by: Bob Stump