I'm currently fighting an issue where EVERY Hyper-V VM we have gives the error "Failed to flush change tracking data before taking a snapshot. Using full scan incremental." This of course, means that Veeam has to read the entire contents of the VHD to back it up, resulting in over 12 hour backup windows and killing us. We have a 2008 R2 based cluster that always had this error and a 2012 cluster that never had the issue. While I thought originally that moving the VM's from the old to the new cluster would resolve the issue, it still persists when the VM's are migrated to the working 2012 cluster. I should mention we're a pure Hyper-V shop.
I've tried many solutions with support. We tried removing all the Veeam components from the hosts and re-installing, didn't help. We disabled CBT and then removed the HKLM\System\CurrentControlSet\Services\VeeamFCT\Parameters\CTBD key, re-enabling CBT then ran a job to see if it would reset, didn't work. I also moved a VM to a stand-alone host, then backed it up but it still came up with the error until I completely isolated it on it's own host and own storage target so it wouldn't reference any old backup sets. I don't have time to evict each node, rebuild them, remove backup sets and start all over again. There's a PowerShell command that can be run, but it errors out with Reset-HvVmChangeTracking : Cannot bind parameter, ect, ect.
As i mentioned earlier, Veeam works great on our 2012 cluster, except for the VM's migrated from our old 2008 cluster. We're relatively new to Veeam and this doesn't reflect well on my decision to choose the product over competitors unfortunately. When it works, it works great! We're still working out the kinks on other small problems too, but this is by far the most annoying issue I have. Has anyone else encountered the error before? I was told by support, that removing all the components, the reg key and re-enabling CBT fixes the problem in their lab but it hasn't for me.