Adding a new hard disk on a clustered virtual machine with multi writer enabled fails with the error "Incompatible device backing specified for device '0'"

Products

• VMware vCenter Server
• VMware vSphere ESXi 7.0
• VMware vSphere ESXi 8.0
• VMware vSphere ESXi

Issue/Introduction

• The operation to add a new hard disk to the first node of the clustered VMDKs on a VMFS datastore failed with the following error: Incompatible device backing specified for device '0'

• The following error message was recorded in the /var/run/log/hostd.log on ESXi host in two separate instances:

  • Disk provisioning method is set to Thick Provision Lazy Zeroed when adding a new disk:

YYYY-MM-DDTHH:MM:SS Er(163) Hostd[2100013]: [Originator@6876 sub=Vmsvc.vm:/vmfs/volumes/vsan:################/################/VM_Name.vmx opID=################ sid=######## user=vpxuser:username] ValidateDiskFileBacking: Virtual disks in multiwriter mode cannot be Thick Provision Lazy zeroed
YYYY-MM-DDTHH:MM:SS In(166) Hostd[2100013]: [Originator@6876 sub=Vmsvc.vm:/vmfs/volumes/vsan::################/################/VM_Name.vmx opID=################ sid=######## user=vpxuser:username] Reconfigure failed: N3Vim5Fault20InvalidDeviceBacking9ExceptionE(Fault cause: vim.fault.InvalidDeviceBacking
YYYY-MM-DDTHH:MM:SS In(166) Hostd[2099944]: --> )

• • Disk provisioning method is set to Thin Provision when adding a new disk:

YYYY-MM-DDTHH:MM:SS Er(163) Hostd[2100013]: [Originator@6876 sub=Vmsvc.vm:/vmfs/volumes/vsan:################/################/VM_Name.vmx opID=################ sid=######## user=vpxuser:username] ValidateDiskFileBacking: Virtual disks in multiwriter mode cannot be thin provisioned.
YYYY-MM-DDTHH:MM:SS In(166) Hostd[2100013]: [Originator@6876 sub=Vmsvc.vm:/vmfs/volumes/vsan::################/################/VM_Name.vmx opID=################ sid=######## user=vpxuser:username] Reconfigure failed: N3Vim5Fault20InvalidDeviceBacking9ExceptionE(Fault cause: vim.fault.InvalidDeviceBacking
YYYY-MM-DDTHH:MM:SS In(166) Hostd[2099944]: --> )

• Verify the disk provisioning type selected for the new hard disk.: Add Hard Disks to First Node for Cluster Across Physical Hosts with Clustered VMDKs on VMFS

Environment

VMware vCenter Server 7.x

VMware vCenter Server 8.x

VMware vSphere ESXi 7.x

VMware vSphere ESXi 8.x

Cause

The failure to add a new hard disk resulted from incorrect disk provisioning selected for a clustered virtual machine with the multi-writer flag enabled.

Resolution

To successfully add a new hard disk to the clustered VMDK primary node on VMFS datastores, Thick Provision Eager Zeroed must be selected for disk provisioning, as this is the only supported configuration.

Reference document:  Add Hard Disks to First Node for Cluster Across Physical Hosts with Clustered VMDKs on VMFS