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| About the vxfenadm utility | ||
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Administrators can use the vxfenadm command to troubleshoot and test fencing configurations.
The command's options for use by administrators are as follows:
The key defined by VxVM associated with a disk group consists of seven bytes maximum. This key becomes unique among the systems when the VxVM prefixes it with the ID of the system. The key used for I/O fencing, therefore, consists of eight bytes.
The keys currently assigned to disks can be displayed by using the vxfenadm command.
For example, from the system with node ID 1, display the key for the disk /dev/sdy by entering:
Reading SCSI Registration Keys...
SCSI ID => Host: 3 Channel: 0 Id: 9 Lun: 0
Key Value [Numeric Format]: 65,45,45,45,45,45,45,45
Key Value [Character Format]: A-------
The -g option of vxfenadm displays all eight bytes of a key value in two formats. In the numeric format, the first byte, representing the Node ID, contains the system ID plus 65. The remaining bytes contain the ASCII values of the letters of the key, in this case, "-------." In the next line, the node ID 0 is expressed as "A;" node ID 1 would be "B."
To confirm whether a disk (or LUN) supports SCSI-3 persistent reservations, two nodes must simultaneously have access to the same disks. Because a shared disk is likely to have a different name on each node, check the serial number to verify the identity of the disk. Use the vxfenadm command with the -i option to verify that the same serial number for the LUN is returned on all paths to the LUN.
For example, an EMC disk is accessible by the /dev/sdr path on node A and the /dev/sdt path on node B.
To verify that the nodes see the same disks
SCSI ID=>Host: 2 Channel: 0 Id: 0 Lun: E
The same serial number information should appear when you enter the equivalent command on node B using the /dev/sdt path.
On a disk from another manufacturer, Hitachi Data Systems, the output is different and may resemble: