Hi all,
I have a p520 machine running 5.2ML9 with a 2Gb FC HBA from IBM, i.e.

# lscfg -vl fcs0
fcs0 U787A.001.DNZ06YM-P1-C3-T1 FC Adapter

Part Number.................80P4543
EC Level....................A
Serial Number...............1F4270A0B6
Manufacturer................001F

Our network administrator is trying to get the host to see some shared storage on our SAN, but reports that the switch sees the host as "UNKNOWN", and states that the HBA needs to be in "initiator mode". However, going into SMIT, I can't see obvious configuration options to use.

The device is seen as "AVAILABLE" as per lsdev -C. Has anyone any idea how this mode should be configured?

Many thanks,
Bookie

Could you post the output of
# lsattr -El fscsi0

Sure - here it is - thanks!

# lsattr -El fscsi0
attach switch How this adapter is CONNECTED False
dyntrk no Dynamic Tracking of FC Devices True
fc_err_recov delayed_fail FC Fabric Event Error RECOVERY Policy True
scsi_id 0x110400 Adapter SCSI ID False
sw_fc_class 3 FC Class for Fabric True

So it seems that the adapter itself knows that it is attached to a switch. Thus from the AIX server side it seems ok. I assume that you have the latest adapter microcode plus AIX driver filesets installed. If you don't - update those first. What you could try then is:
firstly: have the SAN admin switch the port in question off and then on again. Check.
Secondly: if the WWN does not want to register with the switch: delete the fibre channel adapter (from slot to latest device) from the server and re-install.
# lsdev -l fcs0 -F parent
will return a slot e.g. pci03
# rmdev -dl pci03 -R
[in case of DS4K HW you might use rdac and then you need to delete dar and dac devices, too]
After all fcs, fcsi, fcsnet etc. devices are gone run
# cfgmgr

Then test again.

Thanks for taking the time to respond. Will try those things once network guy back in the office.

Thanks again!

Did you post the whole lscfg -vl fcs0 output?
A while ago there was a firmware bug on some adapters and they would not report the whole output, looked just like the output you posted.
If that is all the output you get then call IBM, or the people who supplied the card, and ask for the tool to reflash the card, or for a new card.