A single LUN is attached to my server with rhel5.3. The server has two Fibre channel adapters. I need to turn off one of the FC interface manuly.
Which command should i use to turnoff(disable) the adapter.
The settinga are the following:

#multipath -ll
test-lun (36005076801900139b800000000000150) dm-14 IBM,2145
[size=10G][features=1 queue_if_no_path][hwhandler=0][rw]
\_ round-robin 0 [prio=100][enabled]
\_ 2:0:11:3 sdc 8:32 [active][ready]
\_ 4:0:13:3 sdi 8:128 [active][ready]
\_ round-robin 0 [prio=20][enabled]
\_ 2:0:12:3 sde 8:64 [active][ready]
\_ 4:0:12:3 sdg 8:96 [active][ready]

# cat /sys/block/dm-14/subsystem/dm-14/slaves/sd?/device/state
running
running
running
running

#cat /etc/multipath.conf
defaults {
polling_interval 30
failback immediate
no_path_retry 5
rr_min_io 100
path_checker readsector0
user_friendly_names no
}

multipath {
wwid 36005076801900139b800000000000150
alias test-lun
}
}

Are you trying to verify your multipath device continues to work when one of the fibre connections is gone? If so why not just unplug the fibre cable from the back of the server?

Also you might want to specify what your HBAs vendor/model is (e.g. Qlogic QLA 2430? Emulex?). The answer might be vendor specific.

Hi MensaWater, The HBA is indeed a Qlogic QLA 2430. What i want to do is enable and disable from the command line the adapter (FC) interfce connected to the SWITCH. The Idia is like bringing up and down network interface with "ifconfig" command. Athough I went through the REDHAT documentation about MULTIPATH, and SAN storage conection and communications, I did not find the right answer (smart command to help me out :-)).

hence I thank you ....
looking forward for your suggestion.