<<This is a follow-up to my question of does anyone have non-HP FW SCSI drives on a 3k. What models and how are they configured? Thanks to those on the list who have helped. I paid HP to come and trouble-shoot. At first they weren't a lot of help since my drives are not HP drives. They did it mainly to prove that their controller card was OK. However, I checked the FWD controller card (28696A) and it is differential. The fact that these drives are not differential leads me to believe that is why they cannot be seen on this controller card.>> SE drives definitely will not work with differential adapters, and vice-versa. In fact, this situation turns off the SCSI bus: "The DIFFSENS signal of the connector is used as an active high enable for the differential drivers. If a single-ended device or terminator is inadvertently connected, this signal is grounded, disabling the differential drivers" (SCSI-2 Specification. 5.4.2) And (contrary to my previous thinking) it appears that all "Fast/Wide" SCSI devices HP uses in their mini-class hardware are differential. Which is appropriate, since the SCSI-2 specification specifically recommends against using SE interfaces to "Fast" (i.e. 10MHz) SCSI devices. <<I don't think that configuration or distant has anything to do with it. You may want differential drive when you plan on long SCSI distances. However, I think that non-differential drives cannot be seen by the controller card.>> Definitely not. <<HP brought a FWD drive and it worked fine. It was recognized instantly by MAPPER. What threw me off is the fact that SEAGATE has both ST34371W and ST34371WD model numbers. They also have -WC and -DC drive suffixes. IODFAULT lists the drive without the D. In the single-ended SCSI world, I don't think that differential drives comes into play. In the Fast-Wide SCSI world on the HP3000 I think differential drives are required. I am working with the SEAGATE vendor to trade the ST34371W drives for ST34371WD drives. I will see what happens when the new drives arrive.>> Actually, the lack of the "D" is Seagate's "fault" not HP's; these drives identify themselves to the SCSI adapter with no "D", whether they use a differential interface or not. For example, I have 3 ST15150WDs on an Adaptec AHA-2944W in my PC at home, and the boot-up SCSI-bus-poll shows "ST15150W". Steve