Powering on the virtual machine with snapshots fails

Products

• VMware vSphere ESXi

Issue/Introduction

Symptoms:

• Cannot power on the virtual machine with snapshots
• Powering on the virtual machine that has snapshots fails
• The virtual machine fails when you try to remove a snapshot
• The datastore on which the virtual machine or its working directory is located does not have sufficient space
• In the VMkernel logs, you see an entry similar to:
  
  Nov 27 09:28:04 NMSESX02 vmkernel: 9:18:28:21.630 cpu2:7088)WARNING: Cow: 1436: Opening the cow hierarchy for feeddb9-NMS-EMR_1-000002-delta.vmdk failed with Bad parameter
  
  
• In the vmware.log logfile, you see an entry similar to:
  
  Nov 27 09:38:04.113: vmx| DISKLIB-VMFS_SPARSE :Can't create deltadisk node feeddb9-NMS-EMR_1-000002-delta.vmdk failed with error Function not implemented
  Nov 27 09:38:04.113: vmx| DISKLIB-VMFS_SPARSE : Failed with detail :
  Nov 27 09:38:04.113: vmx| DISKLIB-LIB : Opening COW hierarchy failed!

Environment

VMware ESXi 4.0.x Installable
VMware ESX 4.1.x
VMware ESX 4.0.x
VMware ESXi 4.1.x Embedded
VMware vSphere ESXi 5.0
VMware ESXi 4.0.x Embedded
VMware ESX Server 3.5.x

Resolution

This issue occurs if the last snapshot file of the virtual machine is corrupted.

To resolve this issue, create a clone of the disk using an earlier snapshot and replace the existing disk with the new disk.

To replace the existing disk with a new cloned disk:

1. Provision space on another datastore.
2. Create a folder on the new datastore with the same name as the virtual machine
3. Run this command to clone the disk from the previous snapshot:
   
   # vmkfstools -i /vmfs/volumes/datastore1/virtualmachine/virtualmachine-0000003.vmdk /vmfs/volumes/datastore2/virtualmachine/virtualmachine.vmdk
   
   
4. Edit the virtual machine settings and remove the existing disk.
5. Add the new disk to the virtual machine.
6. Power on the virtual machine.
7. Remove the old files in the original datastore.
8. Perform a Storage vMotion to move the disk to the original datastore.