In vSphere 5 the VMFS filesystem has been updated to version 5 (currently 5.54). In vSphere 4.1 update 1 the VMFS version was 3.46.In earlier versions of ESX, live upgrades of VMFS, or in-place upgrades, haven't been an option so to upgrade VMFS, basically a new LUNs had to be created and then VMs could be migrated to these new LUNs.With vSphere 5, VMFS can be upgraded nondisruptively. This is done for each LUN by going to:Datastore and Datastore...
