We have had 4 machines in the past week get stuck at 65% during routine vMotion as part of DRS. The larger machines become unresponsive after a few hours in this state. My guess is delta file or something eventually chews up enough resources to choke the machine enough that it stops responding. The only way I have been able to fix it is to restart the vCenter service and the Management agents on the host. Then a reboot of the guest.
I grabbed some logs of the server this last happened to, but I could use some help on where to look for issues.
The hosts are running 5.1.0 799733
Just as a precaution I have patched them all to 5.1.0 1065491.
I am not sure if its going to help or not, but I would like to at least try and get some root cause from the previous problems.