Cloning a virtual machine failed

[vulcanus]

We are at the end of a large DR project, which meant migrating many vms to new datastores.  We took a critical machine down yesterday to, instead of migrate (per Vmware support advice) clone it to the new datastore, as it has 1.31TB snapshot.  Cloning is supposed to consolidate this nicely.  It ran for 6.5 hours yesterday.  I kept an eye on the new files on the new datastore.  The last I checked it had copied approx. 700GB in 2 files (one being around 45GB).  I checked back around 10PM to see the new files at the new location are now entirely gone, and the task is no longer running.  Checking events on the parent vm I see "Error: Cloning a virtual machine failed. An error prevented the virtual machine from being cloned."  I searched VMware KBs, but cannot find this specific cloning failure message (tons of others).  I requested the ticket reopened, but since I need answers fast, I'm also posting here.  There is zero information on why this failed in the events.

[dhanarajramesh]

Hi Since you are saying 1.3TB of snapshot found in VM, at that time of VM clone failed, I would suggest you to check the vmkernel logs. I doubt it may be failed due to COW Heap is not enough to consolidate the large snapshot due to some other running VM also using HOW Heap. if you see any error logs regarding COW heap, I would suggest you to free up the host and change default COW Heap from 192 to 256 and reboot and run only clone required server and try again to clone it.