Virtual full synthesis to tape - complete confusion

[conradblack]

Hello all,

My case ID # is 00963017.

I've been running into some confusion with synthesized full backups to tape.

I was told previously on these forums, that I can run a virtual synthetic full to tape daily by enabling this option on the tape job properties and turning off "Process incremental backup files".

I reconfigured my backup methods recently, and here's what I did:

My main disk jobs are running using the forever forward incremental method, and I had previously copied the first full .vbk to tape.

I scheduled my tape job to wait for new backup files, with this schedule being restricted from 12:00 am to 6:00 am. My regular disk jobs were scheduled to run from 12:15 am to 2:00 am and save increments to disk. During this period, the tape job would wait for new files, and synthesize a full .vbk (I scheduled a virtual full synthetic to tape to happen from Tuesday every day through to Saturday).

I checked my Veeam server the next day, and it said there were no new files to backup, even though I had a virtual synthetic full scheduled for that night! I tried running it manually, and the same thing happened.

The next day, I changed my schedule on the tape job and made it run after one of my disk jobs completed (Veeam support told me to change my scheduling). I also checked "Process incremental backup files" because Veeam support told me to do this as well. Once the tape job ran, it synthesized a .vbk and copied every increment.

This was not what I was hoping for! I erased the very same tape, unchecked "Process incremental backup files" and ran the tape job again manually. This time, like magic, a .vbk was synthesized without any additional incremental files being copied! Only one synthesized .vbk was copied, which is precisely what I wanted!

The problem now is... I'm just plain confused. The behavior seems completely unpredictable to me, and I do not know what to think. Veeam support told me I had to have "Process incremental backup files" checked and the documentation also stated this. Do I need this box checked or not, and what is the supported method?

I've read posts on the forums that contradict the notion that this box (Process incremental backup files) must be checked, and now from my testing it seems that this box does not need to be checked (although the behavior is extremely unpredictable). What's up with this and what is supposed to happen? I like how it's working right now, but I don't want to use this method if it's not supported by Veeam fully.

My only inkling on this is that having the tape job wait for new files somehow "broke" it and caused the job to not work as it should, and my "re-jigging" of the job caused it to function normally.

Any further insights would be appreciated!!!

[Dima P.]

Hello conradblack,

I was told previously on these forums, that I can run a virtual synthetic full to tape daily by enabling this option on the tape job properties and turning off "Process incremental backup files".

True.

This was not what I was hoping for! I erased the very same tape, unchecked "Process incremental backup files" and ran the tape job again manually. This time, like magic, a .vbk was synthesized without any additional incremental files being copied! Only one synthesized .vbk was copied, which is precisely what I wanted!

The correct behavior for newly created backup to tape job:

-Synthesized full backup set to create a full every day
-The backup of the incremental files unchecked
-Job schedule set to daily / as a new backup files appear / after this job

If you see any other behavior - it must be investigated and if confirmed sent to QA for a fix. By the way this post might be useful: Synthesized full backup logic