I would do a dmesg ¦more and see if the device is listed there. If not, you can init 0 system and at the OK prompt do a boot -r , that is a reconfigure boot, it will search for all devices connected. I am assuming, of course, you did not add any devices to the scsi chain or change any scsi ID's. Also, make sure it's properly terminated and you don't have a TOTAL length of all cables on the same chain over 6 feet. If your cable length is too long, you should see scsi timeout and retry messages in /var/adm/messages. If all this fails, try a probe-scsi all (check the syntax, my memory fails) at the OK prompt. If it is not found at that level, the OS will not be able to see it. period. Hope this helps...