Unable to add a physical mode disk mapping (RDM) to a virtual machine stored on an NFS datastore

Products

• VMware vCenter Server
• VMware vSphere ESXi

Issue/Introduction

• Unable to add a physical mode, or raw disk mapping (RDM) to a virtual machine residing on a data store connected via network file system (NFS) protocol
  
  
• The vSphere Client or VMware Infrastructure (VI) Client reports:
  
  General System Error
  
• The /var/log/vmkernel logs on the VMware ESXi/ESX host report an error similar to:
  
  NFS: 2243: Unable to create filename.vmdk, nfsclient does not support creation of type: 8
  
• This problem can be encountered when relocating a virtual machine from a VMFS datastore to an NFS datastore. The vSphere Client or VMware Infrastructure (VI) Client reports this error when trying to re-attach an RDM:
  
  A general system error occurred: Internal error and Failed to create virtual disk /vmfs/volumes/path/to/VM/VM_1.vmdk

• A Storage Migration task fails with a compatibility warning:
  
  Virtual disk 'Hard disk 1' is a mapped direct-access LUN which is not supported on the datastore 'NFSvol'
  

Environment

VMware ESXi 3.x
VMware ESXi 4.x
VMware ESXi 5.x
VMware ESXi 6.x
VMware ESXi 7.x
VMware ESXi 8.x

Resolution

The VMkernel routes physical mode SCSI commands directly over the RDM mapping without any modifications. The RDM vmdk pointer file must reside on a VMFS location, therefore the operation fails because the NFS protocol does not support SCSI commands over this interface.

 

When adding an RDM to a virtual machine hosted on an NFS datastore, the Store with Virtual Machine option is grayed out in the Add Raw Device Mapping wizard. Select a specific VMFS Datastore from the available list for the location of the pointer file instead.

Additional Information

For translated versions of this article, see:

• 日本語: 物理モードのディスク マッピング（RDM）を NFS データストアに保存されている仮想マシンに追加できない (2099317)
• 简体中文: 无法向 NFS 数据存储中存储的虚拟机添加物理模式磁盘映射 (RDM) (2113252)