Search the VMware Knowledge Base (KB)
View by Article ID

Unable to add a physical mode disk mapping (RDM) to a virtual machine stored on an NFS datastore (1001856)

  • 8 Ratings


  • 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'


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:



Update History

01/29/2014 - Added ESXi 5.1, vCenter Server 5.1, ESXi 5.5 and vCenter Server 5.5 to products

Request a Product Feature

To request a new product feature or to provide feedback on a VMware product, please visit the Request a Product Feature page.


  • 8 Ratings

Did this article help you?
This article resolved my issue.
This article did not resolve my issue.
This article helped but additional information was required to resolve my issue.

What can we do to improve this information? (4000 or fewer characters)

Please enter the Captcha code before clicking Submit.
  • 8 Ratings