Virtualised MSCS (VMWare)

This relates to vSphere 5.5

Below vSphere 6 MSCS isn’t supported as a guest but even with vS6 it’s only supported with RDMs (Raw Device Mappings).

However you can build a cluster providing you remember the following rules:

  • You CANNOT use vMotion
    • this will create duplicate blanks of the shared disks
    • recovering from this requires deleting the duplicates and then manually re adding the shared disks from within the Virtual Machine configuration
  • the boot and cluster disks MUST be on different SCSI controllers
    • The scsi controller must be ParaVirtual
    • the shared disks MUST be thick provisioned (eager zeroed thick)
  • The cluster validation tool will always show warnings about disk and network but as long as the ERROR messages are cleared it will work
  • Resizing a cluster shared disk reverts it to lazy zeroed thick and you have to ‘eager’ it from the ESX cli as it’s not possible via the GUI.
    • From the correct foler in the correct datastore run
      • vmkfstools –eagerzero nameofvmdk.vmdk

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