I am using a TL2000 tape library with two drives.
The technique can't work if you only have one tape drive.
I'm taking incremental backups Mon-Fri.
Then after the incremental backups are finished on Friday I
consolidate them into a VirtualFull backup.
For a VirtualFull backup to work it takes the previous full backup
and the incremental backups since, and combines them to produce new
tape(s) that will be promoted to being the latest full backups.
The first incremental backups ever run for a host will auto upgrade
to a full backup so you're covered for that.
The process seems to work well for me, after I worked around a minor
problem.
After the incremental backup is complete, tapes are left in the
drives.
If tape X is in drive 1 after the incremental backups are complete
and the VirtualFull wishes to load it it into drive 0 to read from;
then Bacula can't eject the tape from drive 1 and then load it into
drive 0 and deadlocks for user intervention.
User intervention doesn't help either as the tape you want to eject
is locked by Bacula, so you end up stopping daemons and interrupting
the backup.
The solution is to use an administrative job that is scheduled to
eject all tapes from the drives after the incremental backups are
done, and before the VirtualFull backup starts.
Perhaps I should have just raised a bug on that...
Regards,
----------
Jim Barber
DDI Health
