Review the following guidelines to use the vxfentsthdw utility:

• The utility requires two systems connected to the shared storage.

  Caution:

  The tests overwrite and destroy data on the disks, unless you use the -r option.

• The two nodes must have SSH (default) or rsh communication. If you use rsh, launch the vxfentsthdw utility with the -n option.

  After completing the testing process, you can remove permissions for communication and restore public network connections.

• To ensure both systems are connected to the same disk during the testing, you can use the vxfenadm -i diskpath command to verify a disk's serial number.

  See Verifying that the nodes see the same disk.

• For disk arrays with many disks, use the -m option to sample a few disks before creating a disk group and using the -g option to test them all.

• The utility indicates a disk can be used for I/O fencing with a message resembling:

  The disk /dev/rhdisk75 is ready to be configured for 
  I/O Fencing on node sys1

  If the utility does not show a message stating a disk is ready, verification has failed.

• The -o option overrides disk size-related errors and the utility proceeds with other tests, however, the disk may not setup correctly as the size may be smaller than the supported size. The supported disk size for data disks is 256 MB and for coordinator disks is 128 MB.

• If the disk you intend to test has existing SCSI-3 registration keys, the test issues a warning before proceeding.