Powering on the virtual machine fails with the error: The file specified is not a virtual disk (15)

Products

• VMware vSphere ESXi

Issue/Introduction

Symptoms:

• After an offline storage migration from a VMFS to NFS datastore, the virtual machine does not power on
• Powering on the virtual machine after an offline storage migration fails
• In the vSphere Client, you see the error:
  
  Cannot open the disk '/vmfs/volumes/.../VM_NAME/VM_NAME.vmdk' or one of the snapshot disks it depends on. Reason: The file specified is not a virtual disk.
   
• The virtual machine settings displays the disk size as 0, but the Datastore Browser displays correct disk size
• Cloning the disk using the vmkfstools command fails
• Running the vmkfstools -v6 -d thin -i VM_NAME.vmdk VM_NAME_clone.vmdk command displays the error:
  
  DISKLIB-VMFS : "./VM_NAME-flat.vmdk" : open successful (29) size = 32212254720, hd = 0. Type 3
  DISKLIB-VMFS : "./VM_NAME-flat.vmdk" : closed.
  Destination disk format: VMFS thin-provisioned
  DISKLIB-VMFS : "./VM_NAME-flat.vmdk" : open successful (14) size = 32212254720, hd = 183927111. Type 3
  DISKLIB-DSCPTR: Opened [0]: "VM_NAME-flat.vmdk" (0xe)
  DISKLIB-LINK : Opened 'VM_NAME.vmdk' (0xe): vmfs, 62914560 sectors / 30 GB.
  DISKLIB-CHAIN : Disk '/vmfs/volumes/.../VM_NAME/VM_NAME.vmdk' points to itself as parent
  DISKLIB-CHAIN : "VM_NAME.vmdk" : failed to open (The file specified is not a virtual disk).
  DISKLIB-VMFS : "./VM_NAME-flat.vmdk" : closed.
  DISKLIB-LIB : Failed to open 'VM_NAME.vmdk' with flags 0xe (The file specified is not a virtual disk).
  Failed to open 'VM_NAME.vmdk': The file specified is not a virtual disk (15).
   
• In the vmware.log file, you see entries similar to:
  
  | vmx| DISKUTIL: Failed to open and get info for disk: '/vmfs/volumes/4e720900-########-####-##########b8/VM_NAME/' : The file specified is not a virtual disk (15)
   

  Note: The preceding log excerpts are only examples. Date, time, and environmental variables may vary depending on your environment.

Environment

VMware ESX 4.1.x
VMware ESXi 4.1.x Installable
VMware vSphere ESXi 5.0
VMware ESXi 4.0.x Installable
VMware vSphere ESXi 5.5
VMware vSphere ESXi 5.1
VMware ESXi 4.0.x Embedded
VMware ESXi 4.1.x Embedded
VMware ESX 4.0.x

Cause

This issue occurs when the .vmdk descriptor file for the virtual machine boot disk is corrupt or missing.

Resolution

To resolve this issue, create a new .vmdk descriptor file for this disk and then unregister and re-register the virtual machine. This ensures that the vSphere Client detects the correct disk size and the virtual machine powers on properly.

For more information on creating a new descriptor file, see Recreating a missing virtual disk (VMDK) header/descriptor file (1002511).