While running the vxfentsthdw utility, you may see a message that resembles as follows:

Issuing SCSI TEST UNIT READY to disk reserved by other node 
FAILED.
Contact the storage provider to have the hardware configuration 
fixed.

The disk array does not support returning success for a SCSI TEST UNIT READY command when another host has the disk reserved using SCSI-3 persistent reservations. This happens with the Hitachi Data Systems 99XX arrays if bit 186 of the system mode option is not enabled.