Backing up local FSLogix VHDX advice

[Zoatibix]

Hello.

I've been asked to backup a new windows server that includes student's work files. I've not had to backup / restore FSLogix before and the VHDX file is 24.4TB!

The good news is that I have sufficient storage space.

The server has a NAS set as the F: drive of the server. Within that 24.4TB of the 49TB space has been turned into a VHDX file. I've created a normal Windows server backup job, which backs up the drives.

I have a couple of questions about the practicalities of this.

Firstly, as the students only just started I think I'm backing up a lot of white space. Is there a way for VEEAM to handle that? Otherwise I'm thinking it's a case of potentially downsizing that disk to something more sensible.

Secondly, if I needed to restore a few users files would I need to restore the entire VHDX file to another location?

Thirdly, is there a better way of doing this with VEEAM?

Thank you.

(Apologies if this seems hazy but I'm still trying to get some details on this setup.)

[Brad.Barker]

Hello David,

It sounds as though you're using an a Veeam Agent for Window backup to process this, or it's a Hyper-V VM with the VHDX mounted to it, and you're processing the VM. Can you confirm which of these it is?

In either scenario, if you're processing it via a Veeam Agent Backup or a Veeam VM Backup, it should be aware of the white space within the volume and should not consume all that space. In this kind of scenario, you should be able to leverage a normal File Level Recovery. The only real thing I can think of that could complicate any of this approach would be if the VHDX is encrypted with BitLocker. Veeam Agent backups have an option to address the recovery aspect of this though (https://helpcenter.veeam.com/docs/agent ... tml?ver=13), but this is only relevant if that volume is encrypted with bitlocker.

[Zoatibix]

Hello Brad

Yes, it's a Hyper-V VM with the VHDX mounted to it.

I'd looked at this section of the job:

27/02/2026 20:23:17 Succeeded : Hard disk 1 (24.4 TB) 24.4 TB read at 2 GB/s [CBT] (4:07:30)

and assumed it had used up that amount of storage.

However, looking at the Disk Backups I can see -

Data Size Backup Size Data Reduction
24.6TB 180GB 139.8x

So working as you say.

The drive isn't BitLockered.

Thank you for clearing that up. I'd found a few old posts from six years ago which weren't very encouraging.