Storage vMotion to a vVol datastore fails with: Failed to start SvMotion. Error during disk setup.

Products

• VMware vCenter Server

Issue/Introduction

Using storage vMotion fails when the destination is a vVol datastore and the error is a generic "error during disk setup". 

A fatal internal error occurred. See the virtual machine's log for more details.

The vmkernel and vmware.log file have no references to indicate the failed svMotion issue. 

hostd and vpxa show generic failure messages as well with no real details.

-->    reason = "A fatal internal error occurred. See the virtual machine's log for more details.",
-->    msg = "A fatal internal error occurred. See the virtual machine's log for more details.
--> Failed to start SvMotion. Error during disk setup.

The syslog shows the actual reason for the failure:

2025-09-24T15:02:38.759Z Wa(03) worker-2110121 - Mirror: (digest)scsi0:1: SVMotionHandleExistingDisk: Failed: disk '/vmfs/volumes/vvol:examplevolguid/examplefolderguid/examplevm_1.vmdk' has a non-zero size
2025-09-24T15:02:38.759Z Wa(03) worker-2110121 - Mirror: (digest)scsi0:1: SVMotionDiskSetup: failed to remove name reservation for destination disk.
2025-09-24T15:02:38.759Z Wa(03) worker-2110121 - SVMotionPrepareForCopyThread: Failed to start SvMotion. Error during disk setup.

Environment

vSphere 7.x

vSphere 8.x

Cause

A file on the vVol datastore has the same name as a file being migrated to the vVol. vVols will not create an alternate name for the files.

Resolution

Delete or rename the existing file in the vVol. Check to be sure the file is not in use, but it's likely the file is an 0KB orphaned duplicate of what is being moved if the VM was previously on the vVol.