How to restore from differential backup without deleted files?

[Holger_Isenberg]

Is it possible to automatically skip deleted files when restoring from a differential backup? The standard setup is used with daily differential backups and a weekly full backup.

The only reference I can find in the manual about restoring from a pair of full and differential backup is to apply the full restore first and then the differential. There is no option visible to delete files during restore which have been deleted by users between the full and the differential backup.

Of course, this is possible when using the external tool "Intelligent Disaster Recovery" for Windows, but how to do this when restoring a Linux server?

[Ken_Putnam]

You need to setup a "Synthetic Backup" to do what you want

Standard Full/Incr do not and cannot take into account files that were deleted after any one of the backups. After the restore, the deleted files will still be there.

[Holger_Isenberg]

Yes, but then I read on
http://seer.support.veritas.com/docs/270015.htm
that Synthetic Backup is only supported for NTFS volumes where I need it for Linux volumes via RALUS. I have also to check "use archive bit" on the full and incremental backup rules which is not supported by Unix filesystems.

Another document says, synthetic backup via RALUS is possible:
http://seer.support.veritas.com/docs/276382.htm

I will try...Message was edited by:
Holger Isenberg

[Holger_Isenberg]

I tried to modify my policy-based backup job to synthetic backup. With small test backups it worked, but failed during complete backup of a Linux server with a segmentation fault of the beremote process.

However, because of another reason, scheduled synthetic backup is not usable for us as the amount of data on the backup media is the same as a full backup. The advantage seems just to be the reduced network traffic as most of the data is copied from the previous complete backup. Is this assumption correct?

There was a suggestion by Ross Smith on this forum to start a synthetic backup just before and only then, if you do a restore. I don't know yet if that works, and will try...

[Ross_Smith_2]

Heh, I feel famous now :)

No, I'm afraid my synthetic backup suggestion wouldn't work. Veritas confirmed to me that you have to create the synthetic backup there & then within a policy.

I have made a few suggestions to Veritas on the enhancement program though, keep your fingers crossed :)

I'm afraid your only option to ensure deleted files are deleted is to take a full backup every day. Synthetic backups mean your backups take less time, but they still use the same storage on your backup media...

I've seen a lot of problems reported here from synthetic backups. If you've got the time you may as well run a full backup each day.

Depending how much you're backing up, disk storage is cheap these days - I'm rebuilding my backup server next week as a 2TB array for just over £2,000.

Ross