Advanced Disk-based Backup and duplicate tape backups

[Frogbit]

Hi,

We currently create backup-to-disk backups on BEX 10D which are duplicated to tape. Daily incrementals as well as full backups are retained on tape for long periods (7 years!) and restores can be "challanging".

Now moving to BEX 2010 R3 with the Advanced Disk-based Backup Option. Want to use synthetic backups and the True Image restores. I understand that restores can be achieved from backups that have been duplicated to tape and are no longer on backup-to-disk media, but what do I need to duplicate to tape:

The synthetic "full" backup along with the incrementals that follow it? Much as we do now.

or

Is there some magic in the synthetic backup that eliminates the need to duplicate incremental backups to tape? i.e. Will True Image Restore see the synthetic backup along with all the daily changes (incrementals) that went to make it. I doubt this, but just asking.

Remember, we need to restore files created one day and deleted the next that never appear on the weekly full backups, we must retain that incremental data but I am not sure what Advanced Disk-backup Option and True Image Restore expects to have to be able to do this.

Thanks

Paul 

[pkh · Accepted solution]

Once you have done a synthetic backup it is as good as doing an actual backup.  The synthetic backup will incorporate the last full backup (actual or synthetic) and all the subsequent incremental backups since that backup.

From page 917 of the Admin Guide, when doing True Image restores, 

Backup Exec uses the following order of preference to choose the most suitable duplicate backup sets:

■ A backup set in a backup-to-disk folder.

■ A backup set that is on a tape already in a drive, or in a slot of a robotic library.

■ Any other known duplicate copy.

To answer your question, you need to keep a copy of the backup either on disk or on tape.

[Frogbit]

Thanks pkh,

That much I did understand. The question concerned the "granularity" of what the synthetic backup contained when using the "true image" restore feature.

I got the question answered elsewhere (I think!). The synthetic backup contains no magic that true image restore can use: It is pretty much exactly the same as a "full" backup. This is what I suspected. Therefore I have two choices to retain daily "granularity":

1: Duplicate a synthetic backup to tape every day (not really a practical option here - thats a lot of tapes!).

2: Duplicate a synthetic backup at the beginning of the week to tape and daily backups for the rest of the week to the same tape. Apparently "true image" will keep track of this and allow restores for any day of the week for as long as we keep the tapes and catalogues.

I'd still like someone to say "yes, that is exactly what you need to do"!

Cheers

[pkh]

"yes, that is exactly what you need to do" 

Alternatively, you can just duplicate your synthetic backup every week and keep your incrementals on disk. I presume you only need your incrementals until the next synthetic backup.  This way you minimise your tape usage and don't waste time duplicating your incremental backups.

[Frogbit]

Thanks for the confirmation!

As for the other comment: You are presuming too much! We have to have that daily record. Just imagine what happens if we rely only on the weekend's synthetic backups when someone creates a file on Monday and deletes it on Friday. Strange as it might seem, we can be asked to find that file again two years later!

Of course, someone can create a file at 9am and delete it at 5pm and ask for it back a month later... I think there has to be a limit!

We have plenty of room on the tapes to absorb the incrementals along with the preceding synthetic backup so no problem there. As for wasting time duplicating incrementals BEX actually helps out with this one: I only need to run a duplicate job at the end of the week because the duplicate job will remember all five daily incrementals and duplicate the lot in one go. Does anyone else use this back-to-front backup scheme or am I just wierd. No need to answer that!