Shared Multi-writer Disks Inaccessible on VMFS After Storage vMotion From vSAN

Products

• VMware vCenter Server

Issue/Introduction

Symptoms:

• Impacted clustered Linux/WSFC servers are experiencing an application outage because shared disks are no longer accessible following a Storage vMotion.
• When attempting to re-attach the existing virtual disk or enable the Multi-writer flag, the task fails with the following error:
  Operation failed! Task name Reconfigure virtual machine Status: Incompatible device backing specified for device '0'.
• Logs from hostd.log confirm the validation failure:
  ValidateDiskFileBacking: Virtual disks in multiwriter mode cannot be lazy zeroed. Reconfigure failed: N3Vim5Fault20InvalidDeviceBacking9ExceptionE(Fault cause: vim.fault.InvalidDeviceBacking)

2026-03-15T06:15:49.055Z In(166) Hostd[2103342]: [Originator@6876 sub=Vimsvc.TaskManager opID=615ce720-6b-xxxx sid=52df5503 user=<REDACTED>\vpxd-extension-96b840b8-244e-4e78-xxxx-xxxxxxxxxxxx] Task Completed : haTask--vim.vslm.host.CatalogSyncManager.queryCatalogChange-123160 Status success
2026-03-15T06:15:58.585Z In(166) Hostd[2103336]: [Originator@6876 sub=Vimsvc.TaskManager opID=mmhjdny9-12345678-auto-8cahc-h5:xx:xx:xx:xx:xx:xx sid=52df5503 user=<REDACTED>] Task Created : haTask-23-vim.VirtualMachine.reconfigure-123184
2026-03-15T06:15:58.585Z In(166) Hostd[2103336]: [Originator@6876 sub=MetadataTagExtractor opID=mmhjdny9-12345678-auto-8cahc-h5:xx:xx:xx:xx:xx:xx sid=52df5503 user=<REDACTED>] Applied tag : id [Tag rule id=rule[ReconfiguringVm], tag=reconfiguringVm, regex=vim.VirtualMachine.(reconfigure|attachDisk|detachDisk) - Identifies operations resulting in reconfigured virtual machine] to operation: vim.VirtualMachine.reconfigure
2026-03-15T06:15:58.586Z In(166) Hostd[2103336]: [Originator@6876 sub=Vmsvc.vm:/vmfs/volumes/699dc510-xxxxxxx-xxxx-xxxxxxxxxxxx/vmname/vmname.vmx opID=mmhjdny9-14010383-auto-8cahc-h5:xx:xx:xx:xx:xx:xx sid=52df5503 user=<REDACTED>] State Transition (VM_STATE_OFF -> VM_STATE_RECONFIGURING)
2026-03-15T06:15:58.587Z Db(167) Hostd[2103336]: [Originator@6876 sub=Vmsvc.vm:/vmfs/volumes/699dc510-xxxxxxx-xxxx-xxxxxxxxxxxx/vmname/vmname.vmx opID=mmhjdny9-14010383-auto-8cahc-h5:xx:xx:xx:xx:xx:xx sid=52df5503 user=<REDACTED>] Invoking interceptor:1-hbr
2026-03-15T06:15:58.587Z Db(167) Hostd[2103336]: [Originator@6876 sub=Vmsvc.vm:/vmfs/volumes/699dc510-xxxxxxx-xxxx-xxxxxxxxxxxx/vmname/vmname.vmx opID=mmhjdny9-14010383-auto-8cahc-h5:xx:xx:xx:xx:xx:xx sid=52df5503 user=<REDACTED>] Done invoking interceptor:1-hbr
2026-03-15T06:15:58.627Z Er(163) Hostd[2103336]: [Originator@6876 sub=Vmsvc.vm:/vmfs/volumes/699dc510-xxxxxxx-xxxx-xxxxxxxxxxxx/vmname/vmname.vmx opID=mmhjdny9-14010383-auto-8cahc-h5:xx:xx:xx:xx:xx:xx sid=52df5503 user=<REDACTED>] ValidateDiskFileBacking: Virtual disks in multiwriter mode cannot be lazy zeroed.
2026-03-15T06:15:58.627Z In(166) Hostd[2103336]: [Originator@6876 sub=Vmsvc.vm:/vmfs/volumes/699dc510-xxxxxxx-xxxx-xxxxxxxxxxxx/vmname/vmname.vmx opID=mmhjdny9-14010383-auto-8cahc-h5:xx:xx:xx:xx:xx:xx sid=52df5503 user=<REDACTED>] Reconfigure failed: N3Vim5Fault20InvalidDeviceBacking9ExceptionE(Fault cause: vim.fault.InvalidDeviceBacking)
  
  

Environment

VMware vSphere ESXi 7.x
VMware vSphere ESXi 8.x

Cause

• The Storage vMotion process migrated the virtual disk to a "Lazy Zeroed" or "Thin" format on the destination VMFS datastore.
• While vSAN supports Multi-writer on thin-provisioned disks, traditional VMFS requires shared disks using the Multi-writer flag to be formatted as Eager Zeroed Thick to ensure data consistency and prevent metadata locks during allocation.

Resolution

To restore service, the virtual disk must be converted to the required Eager Zeroed Thick format:

1. Power off all virtual machines attached to the shared disk.

2. Detach the virtual disk from all VM nodes.

3. Log in to the ESXi host via SSH and navigate to the directory containing the VMDK.

4. Run the following command to convert the disk format: vmkfstools --eagerzero /vmfs/volumes/<DATASTORE_NAME>/<VM_DIR>/<DISK_NAME>.vmdk

5. Re-attach the disk to the VMs, ensuring the Multi-writer sharing flag is enabled on the SCSI controller/disk settings.

6. Power on the VMs and verify application accessibility.