Update October 6:
VMware released a patch. More info and download here.
A major bug was discovered recently in VMware vSphere 5.5 Update 3. VM’s crash after a snapshot is deleted. In many cases this happens during backup. Crashes are independant on the guest operating system
VMware states this is a major bug. There is no fix yet. There is no KB article yet. The only fix is to downgrade to vSphere 5.5 Update 2.
In a VMware community thread a customer was able to solve this issue by moving the VM folders to the root folder of the datastore. However other customers with VM’s in the root folder also report crashes.
The vmkernel.log shows entry like this Unexpected signal: 11. And [msg.panic.haveLog] , VMware ESX unrecoverable error:
Veeam forum has information here.
At October 1 this was posted in the VMware community:
“Last night engineering found the root cause. They will need to produce an express patch.”
at October 1 VMware released this KB article titled ‘Snapshot consolidation causes virtual machines running on VMware ESXi 5.5 Update 3 hosts to fail with the error: Unexpected signal: 11 (2133118)‘
The article confirms the bug and states there is no fix. It advises customers to downgrade. For large environments the advise is to downgrade a part of the hosts.
According a VMware engineer a patch is expected to be released in two to three weeks!