Migrating a virtual machine with one or more RDMs attached fails with the error: Target disc should be different than the source disc, unable to access file

Products

• VMware vCenter Server

Issue/Introduction

Symptoms:

• Attempting to migrate a virtual machine using vMotion with one or more Raw Device Mappings (RDMs) attached fails.
• You see the error:
  
  Target disc should be different than the source disc, unable to access file

Environment

VMware vCenter Server 5.1.x
VMware vCenter Server 6.x
VMware vCenter Server 7.0.x
VMware vCenter Server 6.0.x

Cause

This issue occurs because the RDM LUN is not visible on the target host.

If the RDM LUN is visible, but it does not always present to the target host, you may see the error:

Virtual Disk 'X' is a mapped direct access LUN that is not accessible

For more information, see Powering on or migrating a virtual machine fails with the error: Virtual Disk 'X' is a mapped direct access LUN that is not accessible.

Resolution

To resolve this issue, configure your storage to allow access for the target host(s) to the RDM LUN(s), and use the rescan command to mount the RDM to the host(s) which did not previously have access to the RDM. For more information, see Performing a rescan of the storage on an ESX/ESXi host (1003988).
Ensure all hosts see the same LUN ID and VML ID for the RDM LUN(s), these are basic requirements which can be found in vSphere Storage Document: Setting LUN Allocations section.

For RDM used as Shared VMDK in Microsoft Windows Server Failover Clustering (WSFC) , remember to set Perennial reservations flag as this is  required in WSFC configuration guidelines,
please follow below KB to check WSFC configuration guidelines, make sure all WSFC configuration meet the requirements:

Microsoft Windows Server Failover Clustering (WSFC) with shared disks on VMware vSphere 7.x: Guidelines for supported configurations

Otherwise, ESXi may take long time to start and vMotion may fail due to storage device related lock issue:

ESXi host takes a long time to start during rescan of RDM LUNs

vMotion fails at 20% for MSCS/Microsoft WSFC VMs with RDM disks

Note: If necessary, contact your storage administrator or storage vendor for instructions on this procedure.

Additional Information

For related information, see:

• Migrating virtual machines with Raw Device Mappings (RDMs) (1005241)
• Cannot see some or all storage devices in VMware vCenter Server or VirtualCenter (1016222)
• Confirming ESX/ESXi host hardware (System, Storage, and I/O) compatibility (1003916)

Confirming ESX/ESXi host hardware (System, Storage, and I/O) compatibility
Performing a rescan of the storage on an ESX/ESXi host
Migrating virtual machines with Raw Device Mappings (RDMs)
Powering on or migrating a virtual machine fails with the error: Virtual Disk 'X' is a mapped direct access LUN that is not accessible
Cannot see some or all storage devices in VMware vCenter Server or VirtualCenter