SCSI-3 PR for IO fencing not supported on VMware ESXi Virtual machines?

We have 6 guest OS (redhat 6.3) on 3 physical machine running VMware ESX5.0,each physical machine has 2 VMs.

And SFCFSHA has been installed.

The fencing disks are three 1GB LUN from physical arrays via VMware RDM physical mode.

but vxfentsthdw test shows:

Testing quanziweb01 /dev/vx/rdmp/ibm_ds8x000_0088 quanziweb02 /dev/vx/rdmp/ibm_ds8x000_0088
 
Evaluate the disk before testing  ........................ No Pre-existing keys
RegisterIgnoreKeys on disk /dev/vx/rdmp/ibm_ds8x000_0088 from node quanziweb01  Passed
Verify registrations for disk /dev/vx/rdmp/ibm_ds8x000_0088 on node quanziweb01  Passed
RegisterIgnoreKeys on disk /dev/vx/rdmp/ibm_ds8x000_0088 from node quanziweb02  Passed
Verify registrations for disk /dev/vx/rdmp/ibm_ds8x000_0088 on node quanziweb02  Passed
Unregister keys on disk /dev/vx/rdmp/ibm_ds8x000_0088 from node quanziweb01  Passed
Verify registrations for disk /dev/vx/rdmp/ibm_ds8x000_0088 on node quanziweb02  Failed
 
Unregistration test for disk  failed on node quanziweb02.
Unregistration from one node is causing unregistration of keys from the other node.
Disk  is not SCSI-3 compliant on node quanziweb02.
Execute the utility vxfentsthdw again and if failure persists contact
the vendor for support in enabling SCSI-3 persistent reservations
================================================================================

I'm sure that the three 1GB LUN from the disk array support  SCSI-3 persistent reservations IF used in physical machines.

But why they do not support  SCSI-3 PR when used in VMware ESX virtual machines?

Is there any up-to-date official guide for configuring I/O fencing for VCS/CFS on VMware ESX?

Thanks!