Veeam and blank pages

[jorgene]

Hi,

I'm going to move a VM which have about 3.5TB data to a different Hyper-V host and location.
Now, the VM consist of number of 500GB VHD files, many of them only have about 100-200GB data in each VHD files but since it's dynamically expanding VHD files most of them now are
500GB in size. If i backup this VM with Veeam and highest compression, how will Veeam hadle all those blank pages in the VHD files?
i.e should i backup this server with veeam directly & should i compact each VHD file first? (for fastest backup window)

The compact operation itself is very time consuming, approx 1hour/vhd file i suspect.

Since it's alot of data i wan't to narrow down the backup window as much as possible, since i need to perform the backup when the VM is offline.

[Vitaliy S.]

If i backup this VM with Veeam and highest compression, how will Veeam hadle all those blank pages in the VHD files?

If you already had data written to these disks and then you removed it, Veeam backup job will read the entire virtual disk image since blocks on these will not be blank, the will be marked as deleted which is not the same. I believe you'd better to run compact operation first and then run Veeam backup job.

Btw, what Hyper-V version are you at? Just found this article that describes how to reclaim virtual disk space, might help: Working with and resizing Windows Server 2012 VHDs

[jorgene]

Hi, yes data has already been written and filled the disks, then much data has been removed inside the VHDs.
As i suspected i now run a compact of one VHD/day since i can't afford more down time on the server each day.
It's currently on a W2008 Hyper-V and will be moved to a W2012.

Then it's the process of converting to VHDX.

[Vitaliy S.]

Ok, then compact operation seems like the only way to go.

[sgatke]

Hi there

I have a question about Veeam (v.7.x) and backup sizes.
Consider this scenario:
Windows 2008 R2 HyperV host
Storage using iSCSI
Windows 2003 guest with a 1.8TB dynamically expanding drive

Let's say that the normal usage for this drive is around 1TB - so the dynamically expanding VHD file is somewhere around 1.2TB in size.
Now, a user uploads 300GB of temporary data to the fileshare. Total data size on disk grows to ~1.3TB and VHD grows to ~1.5TB
After a few weeks (during which Veeam takes backups each night, using reversed incremental) the 300GB of temporary data is deleted.
The VHD size will still be ~1.5GB, but what about the backup files from Veeam?

I would expect the backup size to go back to "normal" (i.e. the size should fall with about 300GB), but am I correct in this assumption?

Thank you in advance.

Cheers
Simon

[veremin]

Hi, Simon, you need to reclaim the free disk space first. See articles referenced above on how it can be achieved. Thanks.