I am finding myself in this really unfortunate situation. We want to use Microsoft Connected Cache which requires Hyper-V. Microsoft Connected Cache is a way to cache inTune installation packages to reduce internet usage.

@Danp Oh for sure!

I have 3 delta backups that backup to an NFS share on a QNAP NAS.

1 of the backups is weekly and the other 2 are daily.

Is that sufficient information or did I forget a detail?

@Danp This is great, thank you. So as long as I migrate the VM, the VM with "[XO Backup weekly-vm-backup]" appended that XO creates will come with it?

I need to migrate VMs to new hardware. The new hardware doesn't have the same number of interfaces and has a bond whereas the current server does not have a bond, so I can't put them in the same pool.

Do I need to start backups fresh after the VMs have been migrated to the new hardware?

@olivierlambert The issue turned out to be a problem with the VHD files. The VM is a Windows VM converted from a physical server with disk2vhd. There were 3 disks in total that I had converted.

To resolve the issue, I created a bootable WinPE.vhd (with storage and DISM tools added) as well as another VHD as a temporary holder for .WIM files. I captured the contents of each VHD from the disk2vhd conversion into .WIM files on the temporary VHD. Then I created new .VHD files and applied the .WIM files to the new VHDs.
After this process, the backups are working.

EDIT (Important): I had to re-create the EFI boot partition and use bcdboot.exe to setup the Windows boot. I also made sure that the new .VHDs had the same drive letters assigned as the originals while in WinPE and have the new .VHDs assigned to the VM in the same order that the originals were.

@olivierlambert oh, yes! That makes more sense. Xen Orchestra is running as a VM on the same host, so it seems unlikely to be a networking issue.

@olivierlambert It only just occurred to me that the "HTTP connection has timed out" could be Xen Orchestra timed out communicating with XCP-ng. If that is the case then more vCPUs and memory on the Xen Orchestra VM wouldn't solve this problem would it...? I suppose I will see.

I have failing backups that leave behind an Export task of a VDI.

I noticed that there are multiple VHD snapshots remaining that are assigned to the Control Domain.

Can I just delete these? The backup error is "HTTP connection has timed out". I have since added more vCPUs and memory to the Xen Orchestra and will see if this resolves the problem, but I want to know if I can delete these remaining VDI snapshots first.

EDIT: I forgot to add that the VM is Windows and has multiple VHDs attached. None of the other VHDs have this issue. Just the one VHD.