HP Fibre Channel Mass Storage Adapters Support Guide, February 2007

Chapter 3

Troubleshooting and Maintenance

fcmsutil

•AD300A

• AB378B

• AB379B

• AB378A

• AB379A

• A6826A

• A9782A

• A9784A

• AB465A

For more information on this command, see the fcmsutil (1M) manpage.

When the fcd driver discovers a new target device, it creates a hardware path for that device based on the

N_Port ID. The N_Port ID is the Fibre Channel address for a device, and a way of identifying the device in a

Storage Area Network (SAN). The fcd driver will also associate a device’s World Wide Name (WWN) with its

N_Port ID.

Each time the fcd driver opens a target device at an N_Port ID, it compares the WWN for the target device to

the WWN of the driver associated with the N_Port ID for that device, when the device was discovered. If the

WWNs are not the same, the fcd driver logs an error message and does not allow access to that device. This

prevents data corruption if a target device is connected through an N_Port ID that belongs to a different

target device; for example, if two JBODs are plugged into each other’s switch ports by mistake.

If you want to intentionally replace a target device, for example a bad disk, use the fcmsutil

<device_file>

replace_dsk

<remote-N-Port-ID>

command to force the fcd driver to recognize a new target device at an

N_Port ID that was previously used by a different target device. The replace_dsk command replaces the

device WWN that is currently associated with a particular N_Port ID with the WWN of the device that is

actually connected through that N_Port ID at the time the replace_dsk command is executed.

The association between a target device WWN and an N_Port ID persists until the system is rebooted, or the

fcmsutil

<device_file>

replace_dsk

<remote-N-Port-ID>

command is executed for that N_Port ID.