Upgrading from VMFS-2 to VMFS-3 Can Make VI Client on ESX Server System Unresponsive (2233)
Note: Before you begin please refer to KB1003490 for important information on restarting the mgmt-vmware service.
To work around this issue, always upgrade one VMFS-2 partition at a time. You should wait at least ten seconds before upgrading the next partition. If the server becomes unresponsive, log in to the service console and restart the host agent using the /etc/init.d/mgmt-vmware restart command.
Other options for this command are stop and start.