When you attempt to migrate a VM with hardware version 10 or earlier to and from a vSphere Virtual Volumes datastore, failures occur if the VM has memory snapshots.

Problem

The following problems occur when you migrate a version 10 or earlier VM with memory snapshots:

  • Migration of a version 10 or earlier VM with memory snapshots to a virtual datastore is not supported and causes a failure.

  • Migration of a version 10 or earlier VM with memory snapshots from a virtual datastore to a nonvirtual datastore, such as VMFS, can succeed. If you later make additional snapshots and attempt to migrate this VM back to vSphere Virtual Volumes storage, your attempt fails.

Cause

vSphere Virtual Volumes storage does not require that you use a particular hardware version for your virtual machines. Typically, you can move a virtual machine with any hardware version to vSphere Virtual Volumes storage. However, if you have a VM with memory snapshots, and plan to migrate this VM between a virtual datastore and a nonvirtual datastore, use the VM of hardware version 11.

Non-VVols virtual machines of hardware version 11 or later use separate files to store their memory snapshots. This usage is consistent with VMs on vSphere Virtual Volumes storage, where memory snapshots are created as separate VVols instead of being stored as part of a .vmsn file in the VM home directory. In contrast, non-VVols VMs with hardware version 10 continue to store their memory snapshots as part of the .vmsn file in the VM home directory. As a result, you might experience problems or failures when attempting to migrate these VMs between virtual and nonvirtual datastores.

Results

To avoid problems when migrating VMs with memory snapshots across virtual and nonvirtual datastores, use hardware version 11. Follow these guidelines when migrating version 10 or earlier VMs with memory snapshots:

  • Migrating a version 10 or earlier VM with memory snapshots to a virtual datastore is not supported. The only workaround is to remove all snapshots. Upgrading the hardware version does not solve this problem.

  • Migrating a version 10 or earlier VM with memory snapshots from a virtual datastore to a nonvirtual datastore, such as VMFS, can succeed. However, the migration might put the VM in an inconsistent state. The snapshots that were taken on the virtual datastore use the vmem object. Any memory snapshots taken after migrating to VMFS are stored in the .vmsn file. If you later attempt to migrate this VM back to vSphere Virtual Volumes storage, your attempt fails. As with the previous case, remove all snapshots to work around this problem.