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tomnewman
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Reset-HvVmChangeTracking not working

Post by tomnewman » Jul 13, 2019 9:31 am

We recently restored a Centos VM and when we next backed it up got the warning "Cannot use CBT: There is no change tracking data available associated with the specified change tracking identifier.. Failed to query changes for disk 'D:\Hyper-V\xxxxxxxx\Virtual Hard Disks\xxxxxxx.vhdx'

We always seem to get this issue when we do a restore, why doesn't B&R do this automatically as part of the restore?

In the past we had B&R installed on the VM Host and using "Reset-HvVmChangeTracking -Server VMhost -HostName "VMName"" worked fine. We recently moved B&R to its own VM and when I have tried to reset the CBT for the recently restored VM I get an error. I have read the KB article and any posts I can find on the forum but haven't found a solution. I am running the command on the VM which hosts B&R.

What I have tried, and the error messages I have received are:

Code: Select all

Add-PSSnapin VeeamPSSnapin
Reset-HvVmChangeTracking -Server VMhost -HostName "VMName"
Error: Reset-HvVmChangeTracking : Unsupported type Microsoft Windows Server of the Hyper-V host VMHost

Code: Select all

Add-PSSnapin VeeamPSSnapin
Reset-HvVmChangeTracking -Server VMHost -VhdPath "D:\Hyper-V\VMName\Virtual Hard Disks\VMName.vhdx"
Error: Reset-HvVmChangeTracking : Unsupported type Microsoft Windows Server of the Hyper-V host VMHost

Code: Select all

Add-PSSnapin VeeamPSSnapin
$server = Get-VBRServer
Reset-HvVmChangeTracking -Server $server "VMName"
Error: Reset-HvVmChangeTracking : Cannot convert 'System.Object[]' to the type 'Veeam.Backup.Core.Common.CHost' required by parameter 'Server'. Specified method is not supported.


Can anybody tell me where I'm going wrong?

Thanks, Tom

tomnewman
Enthusiast
Posts: 47
Liked: 5 times
Joined: Oct 14, 2015 10:12 pm
Full Name: Tom Newman
Contact:

Re: Reset-HvVmChangeTracking not working

Post by tomnewman » Jul 13, 2019 10:22 am

It never ceases to surprise me the number of times i post something or sometimes raise a support ticket then a lightbulb comes on and I understand the problem. It's not like I do these things without first spending significant time thinking about the problem and looking for solutions. Maybe it is the discipline of writing the issue out in detail or just stepping back from it briefly.

Anyway, I found the issue and created a workaround but I would categorise it as a bug and something that Veeam may want to have a look at.

I got thinking about the error Unsupported type Microsoft Windows Server of the Hyper-V host VMHost. Why 'unsupported'? For some reason this reminded me of another problem I had a few months ago so I checked our infrastructure and found that the hyper-v host was present under Managed Servers in both Microsoft Hyper-V and Microsoft Windows. The reason it is in Microsoft Windows is because we use the Hyper-V host as the Mount Server for our Linux repository. It appears that when doing Reset-HvVmChangeTracking it is choosing the 'wrong' VMHost (the one under Microsoft Windows rather than the one under Microsoft Hyper-V), hence the 'unsupported' error message.

To get around the problem, I setup a new Mount Server but used the FQDN for VMHost. I changed the repository to use this new Mount Server and imported all the backups. I then deleted the original Mount Server. Now in the infrastructure I had VMHost listed under Microsoft Hyper-V and VMHost.mydomain.local listed under Microsoft Windows. Reset-HvVmChangeTracking then worked fine.

Surely B&R should check all instances of a name rather than just check the first instance it finds? The information is all present in Get-VBRServer.

As I said, this isn't the first time I have come across this problem of B&R choosing the wrong instance of the server when it was present in two parts of the infrastructure. Unfortunately it was some months ago and I can't remember the circumstances or the problem it caused. This was when we had B&R installed on the VM host and the instance in Microsoft Windows wasn't being used so I just deleted it and it fixed the problem at the time.

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