Hi Symon,

Thanks that feedback. Can you please confirm that Altaro now works fine if:
1) The VM’s to backup have their VHDX files stored on physical drives set up as Storage Spaces mirrors, with the ReFS filesystem.
2) The local target for Altaro backups is a Storage Spaces array formatted as ReFS.
3) The Altaro offsite target server uses Storage Spaces arrays formatted as ReFS

When your documentation states that “The partition must be formatted as ‘Basic’ and not ‘Dynamic'”, are you referring to configuration of the volume of the vDisk within the VM, the volume of the physical disks on the host, or both?

I also assume the vDisk can be configured as either fixed size or dynamic?

As I wrote above, I personally have no need (and see no reason) for ReFS support *within* VMs, so I honestly don’t care if that is supported. If someone has a comment about that and can provide a reason ReFS within a VM is desirable I’d be interested to hear it 🙂

Hi Trevor,

The latest version of Altaro VM Backup supports ReFS, but with some limitations. Here are the support requirements and guidelines. From: https://help.altaro.com/support/solutions/articles/43000483925-what-are-the-system-requirements-for-altaro-vm-backup-

File Level/Exchange Item Level Restore Requirements
The partition must be NTFS/ReFS (through Instant Mount) (only for File Level) formatted
The partition must be formatted as ‘Basic’ and not ‘Dynamic’

Thank you,
Symon Perriman
Altaro Editor

Hi folks,

The latest version of Altaro VM Backup supports ReFS, but with some limitations. Here are the support requirements and guidelines. From: https://help.altaro.com/support/solutions/articles/43000483925-what-are-the-system-requirements-for-altaro-vm-backup-

File Level/Exchange Item Level Restore Requirements
The partition must be NTFS/ReFS (through Instant Mount) (only for File Level) formatted
The partition must be formatted as ‘Basic’ and not ‘Dynamic’

Thank you,
Symon Perriman
Altaro Editor

Andreas is right, ReFS is not supported by Altaro, meaning granular file restores are not possible. I have been asking Altaro to fully support ReFS for years.

I’m aware there used to be an issue with Altaro not being able to use ReFS volumes as a backup target (and is something they should definitely address if they haven’t already), but it has no issues pulling VMs stored on ReFS. I can’t comment on ReFS volumes *inside* a VM, because I don’t create VMs with redundant VHDs… that makes no sense, so I’ve never tried it, let alone tried backing one up.

To reiterate, for those who might be new to ReFS, it should only ever be used where there is disk parity or mirroring – if there’s only one drive, stick to NTFS… Then come back here once you’ve got more drives. While ReFS is highly preferable where there is disk redundancy, unless there are multiple redundant disks don’t assume that its reliability and error checking are fool-proof – just like you should never use RAID5 in any professional production environment, the same goes for storage spaces with a single parity drive.

Where the storage system has been adequately designed and provisioned I’d go so far as to say ReFS is vastly superior to NTFS. This should be immediately apparent, but if you need convincing, I highly recommend spending some time understanding bit rot and self-healing file systems.

Who’s still using hardware RAID? Surely SMBs rarely have controllers with built in checksum data scrubbing (Areca used to do some great cards at very competitive price ranges, but haven’t seen anything from them in years)? RAID cards with such features tend to be very expensive, and the problem with expensive proprietary hardware is it’s usually a single point of failure. That’s something that should be drilled into the foreheads of everyone in IT – eliminate single points of failure. The number of times I’ve seen servers with RAID6, but an expensive controller card that’s five or six years old with no backup card stored carefully in a glass case with a ‘Break in case of emergency’ label…

If you care about data health, you need a filesystem that proactively checks for bad data. If you’re working with cloud storage, that’s already being done by the vendor (Azure actually sits on storage spaces running ReFS). If you’re working with Microsoft based infrastructure you can use ReFS natively – there are other options out there (I’m personally quite partial to ZFS on TrueNAS or FreeNAS where such systems are suitable), but ReFS works out of the box, it performs well (when designed correctly), it’s vastly more reliable than NTFS, and as Eric wrote there are even performance benefits to using it underneath your VMs.

No, I agree, you don’t need to worry about it inside your VMs – the ReFS on the underlying storage will ensure all the data in your VMs remains healthy and free from corruption caused by hardware, whether it’s the VM’s OS or data in a virtualised fileserver. If your VM is writing bad data ’cause there’s something wrong with it, there’s no file system that can help you with that anyway… But you’ve got good backups anyway, right?!

I didn’t know about that. What did support say?

But as this posts are in the context of Altaro Backup, you have to add warning about using ReFS inside VMs when using Altaro.
Backups of ReFS formated volumes look nice, but it is not possible to recover any Data from the backup.
File Granular Restore and mounting virtual disks fails completely.
Recovering the whole volume looks nice but most files are only filed up with empty bytes.

Regards
Andreas