It would be great if vhdx or raw image format is introduced for image backup in urbackup as this will remove the 2TB image backup limitation on common filesystem like - ext4, xfs etc
Also more than 2TB drives like 4TB, and 8TB are available in the market which makes this another reason to have improvement on the limitation with urbackup so that more than 2 TB drives can be backed up for data images.
Please vote for this feature
Isn’t this possible with ZFS raw images?
yes it is, but that makes it dependable to only zfs or btrfs which is not suitable for all scenarios, for example I have a scale-out storage with xfs filesystem and another one with ext4.
ZFS is limited to single physical box and does not scale-out when required.
Adding raw or vhdx image format instead of vhd will remove this dependability and then any filesystem can be used to backup image more than 2 TB.
XFS has reflink support in its newest versions and they are about to not mark it experimental anymore, so UrBackup will support raw images on XFS at some point (and perhaps ReFS on Windows).
But ext4 won’t and you don’t really want a full copy for each incremental file backup, do you?
My only concern is with the 2TB limitation, if that can be fixed in XFS then that will work,
Is there any limitation when we use vhdx for image backups instead of vhd?
Someone has to implement it. It is work 
I’m concerned about the 2TB limit also, but I am unsure if XFS is the direction I would prefer to head. If VHDX’s were to be used, I think that would meet the functional needs I’m looking for, but I also am aiming to use UrBackup with ZFS too. So ZFS is tasty for me too.
I’m interested in using UrBackup for Win/Lin/Mac purposes, so using methods that are more platform-agnostic is preferable. But I like ZFS a lot for its performance and other advanced features, but I am not familiar with XFS.
What are the current thoughts on (an) effective avenue(s) to address this functional need? (larger than 2TB image backups).
Actually I had a thought. Is it possible to use qcow2 file format for this? That might also enable the infinite incremental as seen on btrfs (not sure). Also, if we could backup to qcow2 file formats, that would be tasty for spinning up LinuxKVM VMs from the backup files! 
Or is there a good reason qcow2 file format might not work? I dunno…
I’m banging my head against this limit, my storage won’t support Linux filesystems (limited support for EXT3, a Drobo) & given one of my clients has a 4TB SSD as a boot drive, I’m forced to use a different backup software for a disaster recovery image to a local drive, then do a file backup on the resulting proprietary image over the internet, which causes scheduling difficulties, given I have to only have UrBackup do the file backup when an image by the other software is not running. I foresee this becoming an additional issue with a second client too. Not to mention complicating restore operations.
I know this is an old topic/request, but given the growth in storage time has only made it more urgent. If my storage supported btrfs I’d run a Linux server rather than Windows to work around the issue. Some way of supporting greater than 2TB images with a Windows server is becoming more of an issue as time progresses.
Even raw image format on a Windows server would do, after all, it’s possible to restore those with the Linux restore disk.
I foresee 4TB NVME drives appearing before much more time passing & people using those as a single storage/boot solution.
Sadly I’m no developer, so I can’t contribute :sad
You can use the raw image format with ReFS on Windows now, sadly it doesn’t work with Windows Dedup so you get no compression (or maybe Microsoft fixed that by now).
If I was using a different storage solution I could, Drobo’s “Beyond Raid” system doesn’t work with ReFS, strictly NTFS (or HFS+ for Apple users) and beta support for ext3 which they no longer talk about on their website.
Nice to know there’s a solution when I replace the unit with something better. Free advice: Don’t buy a Drobo.
I forget which way round right now, but hard links & dedup are both things Microsoft added for ReFS, unfortunately neither is supported in Server 2012R2 I’d need to go to 2016 for one & 2019 for both.
Basically they’re modifying the feature set quite often & sometimes requiring a reformat with a higher Windows version to enable new features, as such I’m still treating ReFS as being in beta. At least while I remain on 2012R2.