backing up datastores, what if one VM is on many?

[Dude]

There's http://www.veeam.com/blog/vm-backups-forget-me-not.html mentioning that when using Veeam to back up datastores instead of VMs any VMs on a datastore are inventoried and backed up.

What if a VM is on multiple datastores? Let's say that a VM has four disks, two are on Tier 1 and two are on Tier 2 storage. If I select to backup that particular Tier 1 datastore, the VM will be inventoried and backed up, but in doing so it will either pull data from the Tier 2 datastore as well, or it will not include that data and the VM backup will be incomplete at best or unusable at worst?

If it does pull data from Tier 2 during the Tier 1 backup, will it also pull data from Tier 1 during the Tier 2 backup and thus create quite a bit of duplicate data in the backup set? If there was global deduplication this wouldn't be an issue, but since the dedup is per job only this could create significant duplicate data stored.

Thoughts?

[veremin]

Regardless of what datastore is chosen as the source, VB&R will perform full VM backup. Thanks.

[Dude]

Thanks for the quick answer. Let me just confirm that I understand this correctly;

VM has 4 disks, let's just say that they are all 500 GB each, two disks are on datastore1, two disks are on datastore2.

VBR Job1 backs up datastore1, which will contain all the VM data, for a total of 4 disks * 500 GB = 2 TB (not counting compression, dedup, etc).
VBR Job2 backs up datastore2, which will also contain all the VM data, for a total of 4 disks * 500 GB = 2 TB (not counting compression, dedup, etc).

So if I have a VM that is spread out across multiple datastores, and each datastore is backed up by a separate job, then I will end up with multiple full copies of that particular VM?

[veremin]

Yes, your understanding is correct. However, you can add the given VM(s) to the exclusion list of one job in order to prevent data duplication. Thanks.

[Dude]

Excellent suggestion, thanks!

[veremin]

You're welcome. Should any other help be needed, don't hesitate to let us know. Thanks.

[npandav]

Is this still the case with Veeam 9.5 Update 3?

We have the same kind of set up where VM's have disks located on multiple datastores.
Do we still need to exclude these VM's from other datastore backups?

What happens when we vmotion the VM to another datastore? do we then need to update the backup job?

[foggy]

Hi Naresh, yes, this is still the case - the entire VM is backed up even in case only one of the datastores containing its disks is added to the job. As for the migration scenario, it depends on what disks are actually migrated to what datastore (whether it had this VM's disks before the migration or not and whether this VM was excluded in the corresponding job). Thanks.