Posey's Tips & Tricks
Top 4 Errors When Backing Up Hyper-V Guest Clusters
Hyper-V guest clusters can be a handy tool for providing application-level resiliency for your mission-critical workloads. Even so, the use of guest clusters adds an extra layer of complexity to your workloads -- complexity that has occasionally been known to cause problems with backups.
As such, I wanted to take the opportunity to talk about some of the errors that can occur when backing up a guest cluster.
Before I get started, I want to quickly point out that the error messages that I will be discussing are generated by the Windows operating system. Even so, it's very possible that the error messages will be displayed by your backup application, even if you are using a third-party solution.
With that said, let's take a look at the error messages.
1. Failed To Create Checkpoint on Collection 'Hyper-V Collection'
One error message that you may occasionally encounter is "Failed to create checkpoint on collection 'Hyper-V collection.'" This message may be accompanied by error code 32768.
The root cause for this error message is usually the host operating system being unable to query the cluster service that is running inside of the guest virtual machine (VM). In most cases, the way that you would fix this error is to log on to each one of the virtualized cluster nodes, then check to make sure that the failover cluster feature is installed within each node and functioning correctly.
Although a failover cluster feature failure is normally the thing that causes this error, it is not the only potential cause. It is also conceivable for the error message to occur as a result of integration services not running on the VMs, incorrect firewall rules or a VM that is connected to the wrong virtual switch.
2. Active-Active Not Supported for Shared VHDX in VM Group
Another somewhat common error message is "Active-active not supported for shared VHDX in VM Group." This error is sometimes displayed with error code 32770.
If you receive this error message, it's a clear indication that the shared virtual disk set is being used as a cluster-shared volume. The reason why this is a problem is because Hyper-V cannot create checkpoints for a cluster-shared volume.
To fix the problem, you need to use the Remove from Cluster Shared Volume option and use the VHDS disk simply as a shared disk.
3. More than One VM Claimed To Be the Owner of Shared VHDX
Another error that sometimes occurs is "More than one VM claimed to be the owner of shared VHDX in VM group 'Hyper-V collection.'" The error code that is associated with this error message is 32775.
There are a couple of different things that can cause this particular error message to occur. First, you may receive this error message if you try to use a Windows Server 2012 R2 VM to connect to a VHD set disk. VHD set disks are only supported by VMs running Windows Server 2016 and above.
The other reason why this error may occur is the guest cluster sees the shared disk as being offline. Assuming that your guest cluster nodes are running the correct version of Windows Server, you can usually fix the problem by simply making sure that any shared disks that are used by guest clusters are online and accessible.
4. 'BackupVM' Background Disk Merge Failed To Complete
Finally, you may occasionally receive an error message stating, "'BackupVM' background disk merge failed to complete: General access denied error (0x80070005)." The error code accompanying this particular error message is Event ID 19100.
This error indicates that there is a permissions problem. Hyper-V (or more precisely, the Virtual Machine Management Service) is unable to access the shared disk, the snapshots or both. To fix the problem, you will need to delve into PowerShell. Fortunately, only two commands are required, and neither is overly difficult.
The first thing that you will have to do is to retrieve the VM's ID. You can do this by entering the following command:
Get-VM | Format-List Name, ID
Once you know the VM's ID, then you will have to use the icacls command to grant access to that VM. Here is the command that you will need to use:
Icacls <the path to the folder containing the VHDS files> /grant "NT VIRTUAL MACHINE\":(OI)F
Brien Posey is a 16-time Microsoft MVP with decades of IT experience. As a freelance writer, Posey has written thousands of articles and contributed to several dozen books on a wide variety of IT topics. Prior to going freelance, Posey was a CIO for a national chain of hospitals and health care facilities. He has also served as a network administrator for some of the country's largest insurance companies and for the Department of Defense at Fort Knox. In addition to his continued work in IT, Posey has spent the last several years actively training as a commercial scientist-astronaut candidate in preparation to fly on a mission to study polar mesospheric clouds from space. You can follow his spaceflight training on his Web site.