Guest backups and SAN drives

[Lancegaydon1]

Hopefully this will make sense!

Say I have a VM guest that has a 50 gig drive as the c:

I then attach 5 drives from the SAN that show up in disk management, and say they are all 10 gigs in size.

I then use vcenter to take a backup of the whole VM, how big should that backup be? Should it just be 50 gigs? Or would it be the 50 gigs plus the 50 gigs of SAN drives since they show up as drives within the disk management? Or is the backup smart enough to know that it should only take the c:?

Thanks for any clarification!

[AndreTheGiant]

It depends by the backup program type.

Usually the backup is smaller than the total vmdk amount size, cause unsuded space may be not saved (like VCB do).

If the backup program can make compression and/or deduplication and/or incremental than the size could be more small.

Andre

[Lancegaydon1]

We are using the builtin backup with vcenter, not VCB or anything

[AndreTheGiant]

Do you mean VDR?

In this case it support deduplication and incremental backup, so after the first full backup, the required space could be quite small.

Andre

[Lancegaydon1]

Yes.

Howevere that doesnt really answer my question, perhaps I am not phrasing it correctly. I want to know how big the full backup will be in my given scenario as a one time shot, not to do with incrementals or anything.

Thanks

[AndreTheGiant]

Also in a one time shot the deduplication can help to reduce the space.

But this depends if there are VMs that are similar, or maybe that came from the same template.

Andre