Thinking a bit about it, we realized that we had installed the HP Lefthand MPIO DSM on the backup server. Normally we do not install any MPIO DSM on the backupserver because most of the VMware backup products do not work well with MPIO drivers. But this time, we do not plan to use such kind of products and therefore installed the DSM to get proper failover and loadbalancing.
Searching on the internet I found the blog from Rhys Goodwin and he suffered the same problem. He figured out that installing the DSM can cause severe problems on VMware datastores because of locking mechanism used by the DSM.
TO FIX:
1.Uninstall HP Lefthand DSM for MPIO from Windows hosts (We still want to try to present the VMFS LUNs back to the backup server at some stage)
2.Shutdown all VMs
3.Shutdown all the ESX hosts
4.Shutdown Lefthand (Shut down the management group, not the nodes individually)
5.Power up the Lefthand and make sure all the nodes are up and volumes are all online
6.Power up the ESX hosts and VMs
2.Shutdown all VMs
3.Shutdown all the ESX hosts
4.Shutdown Lefthand (Shut down the management group, not the nodes individually)
5.Power up the Lefthand and make sure all the nodes are up and volumes are all online
6.Power up the ESX hosts and VMs
