I know "delete snapshot takes forever" posts are a dime a dozen - but this one is quite different.
Last night, Backup Exec took a snapshot of a server for backup purposes. It completed that backup only a few minutes later, and started deleting the snapshot.
That snapshot has been deleting for over 12 hours, a task which usually completes in minutes. To make matters worse, the server itself has become unresponsive. The host is ESXi 5.1, and I because of the active "Remove snapshot" job, I can't restart the VM or anything like that.
Any assistance appreciated.
Did you checked this KB: Unable to commit virtual machine snapshots because another task is in progress (1010310)
You can use the monitor commands available in KB http://kb.vmware.com/kb/1007566 to monitor the progress of the snapshot.
first, try to look to vmkernel and hostd logs on that ESXi host, you should find there some errors regarding snapshot deletion.
After this you can try some troubleshooting based on your findings.
Here are some useful links to KBs with similar issues: