Virtual Machine Migration Fails

After recently upgrading a customer to vSphere 4.1 Update 1, I received a call from the customer because one of their guest VMs could not be migrated to a different VMFS datastore.  The somewhat troubling, “unable to access file” error message indicated a problem with the VMDK for a specific snapshot.

Through an SSH session I validated the snapshot VMDK and VMDK flat file existed in the proper directory.  The VMDK flat file had a non-zero size, suggesting to me this might be a configuration problem.


Out of curiosity I examined the snapshot’s VMDK configuration file and noticed the parentFileNameHint entry contained the full pathname and used the VMFS GUID value.  Hmm.  Is that the proper GUID?  No it wasn’t.


Since the VM had other snapshots I reviewed those configuration files as well and noticed they used relative path names for the parentFileNameHint.  Could it be that simple?
I edited the snapshot VMDK configuration file and removed the full path qualification.  


Problem solved.


In my example above (which was reproduced in my lab), I changed:
parentFileNameHint=”/vmfs/volumes/4ab3ebbc-46f3c941-7c14-00144fe69d58/retro-000001.vmdk"
To:
parentFileNameHint="retro-000001.vmdk"

Virtual Machine Migration Fails