Synthetic full frequency

[gtech1]

I would like to backup some VMs about once a month and keep 9 restore points.

Ideally I'd like to perform a synthetic full every 4 backups.

So basically it would be:

Full
Incremental
Incremental
Incremental
Synthetic full
Incremental
Incremental
Incremental
Synthetic full

But I'm not sure how to configure this in VBR (?). Synthetic full can only be configured to run every x weekdays, not every x restore points. Or am I missing something ? Is it even possible to do what I want ?

[HannesK]

Hello,
and welcome to the forums.

Question: what's the reason for creating synthetic fulls. On REFS & XFS (the recommended file systems), they are just a "helper" for GFS (weekly, monthly, yearly) restore points and some other scenarios. There is no technical requirement for synthetic fulls.

Correct, you can only configure synthetic fulls on a specific day. As workaround, you could have a script, that is permanently changing the job settings, but overall it makes little sense to me without further explanation.

Best regards,
Hannes

[gtech1]

well, how else should I approach this ? I don't want to have 1 full backup + 8 incrementals. I also don't want to do 8 full backups as it's too resource intensive and the changes are small in these VMs. Can I program B&R to do 1 full backup every X restore points ?

[HannesK]

I don't want to have 1 full backup + 8 incrementals

what's the reason for that?

I also don't want to do 8 full backups as it's too resource intensive and the changes are small in these VMs.

with XFS / REFS, it's spaceless / no resources needed

Can I program B&R to do 1 full backup every X restore points ?

only with a workaround like mentioned above: scripting

[gtech1]

It would still be intensive on the source host, doing full backups for no good reason, regardless of the backup destination.

If I may offer this suggestion, I think this scenario would be beneficial to allow creation of synthetic full backups after X incrementals

[Gostev]

It would still be intensive on the source host, doing full backups for no good reason, regardless of the backup destination.

No it's not. At least not with Veeam. Synthetic full does not create any additional load on the source host comparing to an incremental backup.

[gtech1]

That's what I'm saying. There is no difference on the source for host doing either incremental or synthetic full. There is however an additional load if I do FULL backups every single time, which is what I'm trying to avoid.

It seems like a pretty basic feature, no ? To be able to do synthetic full after X incrementals instead of every "X" day of the week.

[Gostev]

No, actually there is no additional load even if you do synthetic full backups every single time.

In case you want to create synthetic fulls more often than just once per week, this is possible already. You can easily select multiple days per week to do synthetic fulls on. For example, you can have fulls happening every 3-4 days (as you asked in the very first post) by scheduling them on Wednesday and Saturday.

[HiHoItsOffToWorkWeGo]

@gtech1 said:

I would like to backup some VMs about once a month and keep 9 restore points.
I want it to look like this:
Full
Incremental
Incremental
Incremental
Synthetic full
Incremental
Incremental
Incremental
Synthetic full

Although with Veeam it's going to look like this instead, if you're using the recommended REFS or XFS file systems, this doesn't take up any more storage space or consume any more resources during backup or take any additional time, than what you wanted:
Full
Synthetic full
Synthetic full
Synthetic full
Synthetic full
Synthetic full
Synthetic full
Incremental
This is because unless told not to create them at all, Veeam will create synthetic fulls at least once a week.

[RubinCompServ]

what's the reason for that?

While I haven't had to go as low as a Synth full every 4th backup, I've found that my customers with more than 30 incrementals in a single chain routinely run in to errors when attempting to perform a recovery. Since they need to keep 30 days-worth of an every-4-hours backup job, they run a Synthetic Full every Sunday morning, but that still leaves them with 42 points in the chain.

[HannesK]

hmm, that sounds environment specific... we have customers doing 180 or 365 (I believe to remember, even 720 days) increments without any issues since many years. As you found a workaround, I guess that you did not open a support case for that behavior?

[RubinCompServ]

I had opened a case but we never reached a real resolution. It was some years ago so my memory is sketchy, but I think I recall increasing a timeout value in the registry to something like 3 hours but that still didn't resolve it and the case stalled out, so we just went with weekly Synthetic Fulls instead.