Synthetic Backup Disk-2-Disk-2-Tape

[Bodo_Josefy]

Hello,

is it possible, and how, to create a policy for a synthetic backup to disk and after that to tape ?

It should work this way:
A) Running a baseline job once (to disk)
B) Running an incremental job every day (to disk)
C) Running a synthetic backup every day (to disk).
D) Copying the synthetic backup to tapes every day
(overwritten after one week, the Friday's tapes brought off-site)

I can see the following advantages:
* Very fast incremental backup, because the baseline AND the incremental files are on disk
* Very fast synthetic backups for the same reason
* The last full backup is always on disk (very short restore time)
* Full backups of one complete week on tape (short restore time because no incremental restores necessary)

Disadvantages:
* Tape capacity (because a full backup is written to tape every day for 5 days)
* Disk capacity (because I need at least two full backups on disk - the baseline and the synthetic backup)

Questions:
* Does the synthetic backup (Step C) handle deleted/renamed files correctly (is a deleted file also deleted from the synthetic backup) ?
* Does the synthetic backup (Step C) automatically become the new baseline for the next day's incremental backup ?
* If yes, this means after two days the synthetic backup is not needed any more because the next synthetic backup has become the new baseline
* So I would like to configure the policy in that way that the synthetic backups overwrite baseline backups from two days ago. That means, baseline and synthetic backup are "switching" every day.
* For this scenario to work, i must set the overwrite protection for my to-disk-media to one day (that means, after two days it is overwritten with the new version)
* I see the problem if one day - for any reason - the synthetic backup does not run. Then the next day all my to-disk-media (bkf files) is not protected. It would be possible that the synthetic backup overwrites the baseline backup which is needed to run the synthetic backup at all ?

Has anybody tested or even implemented such a scenario ?

Many thanks for your comments !

Bodo

[Amruta_Purandar]

Hello,

The synthetic backup feature eliminates the need to perform recurring full backups for
supported remote resources. A policy created for the synthetic backup feature enables the
synthetic backup to be assembled from a full backup (called a baseline) and subsequent
incremental backups that are also contained in the policy.
The resulting synthetic backup then becomes the new baseline, so only incremental
backups are required until the next synthetic backup is created. The synthetic backup is
as current as the last incremental backup that it contains.
The components of the policy for synthetic backup are:
a. Baseline. The first backup to run that is associated with the synthetic backup. The
baseline backup runs one time only, and will always back up all of the files on the
selected resources when it runs.
b. Recurring incremental backups. Subsequent backups that back up files that are
changed after the baseline backup. After the baseline backup completes, at least
one incremental backup is necessary.
c. Recurring synthetic backups. The process that combines the data from the
baseline backup and the incremental backups to form a synthesized full backup of
the selected resources. This synthesized full backup becomes a new baseline
backup, which can then be combined with subsequent incremental backup sets to
form the next synthesized full backup.

Questions:
* Does the synthetic backup (Step C) handle deleted/renamed files correctly (is a deleted file also deleted from the synthetic backup) ?

- Yes

* Does the synthetic backup (Step C) automatically become the new baseline for the next day's incremental backup ?
- Synthesized full backup becomes a new baseline
backup, which can then be combined with subsequent incremental backup sets to
form the next synthesized full backup.

* If yes, this means after two days the synthetic backup is not needed any more because the next synthetic backup has become the new baseline
- Not the previous but the recent backup is required.

* So I would like to configure the policy in that way that the synthetic backups overwrite baseline backups from two days ago. That means, baseline and synthetic backup are "switching" every day.
- Please elaborate. How do you mean "switching"?

* For this scenario to work, i must set the overwrite protection for my to-disk-media to one day (that means, after two days it is overwritten with the new version)
- Yes if you are bcking up to the same media.

* I see the problem if one day - for any reason - the synthetic backup does not run. Then the next day all my to-disk-media (bkf files) is not protected. It would be possible that the synthetic backup overwrites the baseline backup which is needed to run the synthetic backup at all ?
- Please elaborate

Please refer the followign technotes as well.

Title:
The basics of Advanced Device and Media Management for VERITAS Backup Exec (tm) for Windows Servers
http://support.veritas.com/docs/192265

Title:
An explanation of the "Overwrite Protection Period" and the "Append Period"
http://support.veritas.com/docs/237374

NOTE : If we do not receive your reply within two business days, this post would be marked assumed answered and would be moved to answered questions pool.

[Sven_Martin]

I have the same issue.

If you backup to disk, you will need space for 1 baseline backup (or synthetic) + incremental backup + new synthetic backup. Which is actually minimum double the size of what you are trying to backup. If the overwrite protection is set to 1 day, my incremental backup will not overwrite the baseline (or synthetic) backup if it is run the next day. But what happens if for some reason the incremental and next synthetic cannot run or what happens after a weekend. In this case the 1 day overwrite protection has passed and my incremental will overwrite the baseline (or synthetic) and thus the new synthetic will fail and thus the next incremental will actually be a full again.

I have tried to set it up, and what looks great in theory doesn't work in real life so far. I hopr you can give me some best practices on this. Don't redirect me to the online documents because they do not explain what I want to achieve.

Thanks, Sven