Differential Proposed Setup

[Tim_Rainier]

I wanted to setup a backup policy which creates a full backup on Sunday and does 6 daily differential writes to the same tape for the remainder of the week.

Is this doable? How should I go about? Is this a bad idea? Should I use 1 tape for full and 1 tape for the differentials instead?

[DavidParker]

Tim,
Yes, you can put both full and incremental jobs onto the same tape if you want, as long as they have the same retention levels. Just setup the policy to use volume pool and both schedules will write to tapes in that VP by default.

Otherwise, I would use 2 different Volume Pools (1 for Full or Weekly jobs and 1 for Incremental or Daily jobs).

Do you have a tape library?
If you do, you may wind up with some of the backups on more than 1 or on different tapes unless you really restrict how the policy runs.

Can you elaborate a little more on your setup?
Master version? Tape library? Number of clients? Multi-streaming? etc

[Stumpr2]

Hello Tim,
I am curious as to why you want to put all your eggs in one basket. perhaps when you answer Dave's questions about your environment, it may make sense.

If you put your Full and all incrementals on the same tape, what happens if that tape is accidently dropped to the floor or somehow becomes becomes corrupted? I have seen some Netbackup customers get so paranoid that they request a different tape for each of the fulls and also a different tape for each of the incremnentals. Turns out something like.

Week1_Fulls
Week2_Fulls
Week3_Fulls
Week4_Fulls

Monday_Incr
Tuesday_Incr
Wednesday_Incr

etc.....

How about creating duplicate images that would combine the originals unto a single tape? That is easy to do if you use the same retention for the fulls and incrementals.

[Tim_Rainier]

Actually, that's specifically what I'm trying to do. And it fails because it "freezes" the media and I can't use the media again until I expire it.

[Tim_Rainier]

Obviously I see the problems with this scenario.

But, in the same respect, what happens if I lose the full tape? My differential tape(s) is/are useless?

I guess I'm trying to save tapes. Maybe it's not worth it. I know for a fact, though, that I'm not going to be in there every day swapping a tape out. heh

We do have a library, though. And it would be pretty simple to set up a full tape, then a daily differential tape.

[DavidParker]

Tim,
You should probably try to find out why your system is freezing the media, I think.
It shouldn't get frozen unless there are problems.

If you need to re-use the media, you can unfreeze it without expiring it:
use the bpmedia -unfreeze command

[Tim_Rainier]

Yeah, I mis-spoke. It's not freezing it. It's just because of retention and expiring the media is what I have to do to write back to the tape. Why is that?

[DavidParker]

I'm guessing that you have different retention periods on your full and incremental jobs?

By default, NetBackup wont let you put different retention periods on the same media; you have to specifically enable that option in the Media section of the Master's Host Properties.

Perhaps this is what is causing the behavior you're seeing?

[Tim_Rainier]

Can't I just append jobs to the tape? What if I don't want to use any retention period?

[DavidParker]

I don't think you can 'not use' a retention period; I believe it's a required part of a policy setup.

Unfortunately, I don't think you can force a particular backup to append to a particular tape unless you meet whatever requirements NetBackup has. If the volume pools and retentions match, it may put the next backup onto the same tape. But it could also very well put it onto another tape in that volume pool.