Virtual RDM (vRDM) to flat disk conversion with Storage vMotion task fails with error "A specified parameter was not correct: spec.disks.diskBackingInfo"

Products

• VMware vCenter Server

Issue/Introduction

• Unable to convert virtual RDM to vmdk.
• Below errors are seen in vCenter server UI and vpxd.log :
  
  UI - "A specified parameter was not correct: spec.disks.diskBackingInfo"
  vpxd.log - Invalid backing type (vim.vm.device.VirtualDisk.RawDiskMappingVer1BackingInfo) specified in RelocateSpec

--> (vim.vm.RelocateSpec.DiskLocator) {
--> diskId = 2016, 
--> datastore = 'vim.Datastore:#######-c8a1-403a-####-#####:datastore-12345', 
--> diskMoveType = <unset>, 
--> diskBackingInfo = (vim.vm.device.VirtualDisk.RawDiskMappingVer1BackingInfo) {
--> fileName = "ds:///vmfs/volumes/12345678-123456-1234-12345678/example/example.vmdk", 
--> datastore = 'vim.Datastore:#######-c8a1-403a-####-#####:datastore-12345', 
--> backingObjectId = "", 
--> lunUuid = "0100000000#####################################################################6572766572", 
--> deviceName = "vml.0100000000#####################################################################6572766572", 
--> compatibilityMode = "virtualMode", 
--> diskMode = "independent_persistent", 
--> uuid = "6000C29e-####-732a-3eff-###########", 
--> contentId = "#########################################", 
--> changeId = <unset>, 
--> parent = (vim.vm.device.VirtualDisk.RawDiskMappingVer1BackingInfo) null, 
--> deltaDiskFormat = <unset>, 
--> deltaGrainSize = <unset>, 
--> sharing = "sharingNone"
--> }, 
--> profile = (vim.vm.ProfileSpec) [
--> (vim.vm.DefinedProfileSpec) {
--> profileId = "11ba3e8d-####-4b7a-8ca6-################", 
--> replicationSpec = (vim.vm.replication.ReplicationSpec) null, 
--> profileData = (vim.vm.ProfileRawData) null, 
--> profileParams = <unset>
--> }
--> ], 
--> backing = (vim.vm.RelocateSpec.DiskLocator.BackingSpec) null, 
--> filterSpec = <unset>
--> },

Environment

vCenter 8.0.x
ESXi: 8.0.x

Cause

Using the volume allocation policy with the virtual machine and keeping the format same as source, for the the vRDM disk the diskBackingInfo is set to RawDiskMappingVer1BackingInfo during migration. RawDiskMappingVer1BackingInfo cannot be converted to FlatVer2BackingInfo, SeSparseBackingInfo.

Resolution

Dissociate the SPBM policy from the VM :
1. Right click on the VM --> VM Policies --> Edit VM Storage Policies --> Change the policy to datastore default --> Ok
2. Migrate the virtual machine

Additional Information

For more details on "vSphere Storage Policies and Virtual Machines" refer LINK