Some weeks ago we hit an issue whereas storage vMotion failed and operation rollback caused 10 to 15 minutes freeze of the affected VM.
It turned out that this only happend to bigger VMs meaning more then 300GB RAM configured. There is finally a KB available by VMware but the workaround they provide needs you to shutdown the affected VM. This was not an option to me so i decided to go the PowerCLI way!
$vm = get-vm VMName New-AdvancedSetting -Entity $vm -Name sched.mem.pshare.enable -Value false
This will disable the pSharing Feature. After setting this, you have to vMotion the VM to a new host, that will recreate the world and reload the vmx thus enabling the new setting.
After this I was again able to do storage vMotion and everything beeing kept online.
Hope this helps.