Date: Mon, 27 Oct 2003 20:23:24 -0800 (PST) From: Gregg Eshelman <[EMAIL PROTECTED]>
A 68 to 50 pin "narrow" adapter must include active termination of the high byte. The 68 pin devices then must all be between the controller and the 50 pin devices.
Alternatively, if your adapter does not terminate the high byte (top 18 wires) then you should put your 68 pin drive at the end of the SCSI cable, and enable termination on the 68 pin drive--assuming it is not a U2W drive which does not have on-board termination. In this configuration, you are limited to one and only one adapted 68 pin drive on the cable because it must go at the end of the cable.
These complications of termination are why I strongly recommend against folks using adapted drives, including the widely available SCA drives. If you know what you're doing it can be made ot work, but if you don't know, and aren't inclined to carefully study SCSI termination issues, then adapting a 68 pin or 80 pin drive to a narrower bus is a *bad idea*.
To make things worse, SCSI voodoo, as its called, happens because sometimes (often) SCSI will appear to work even when you configure things incorrectly. This can lead to unnoticed corruption of your devices, or just a bus that works okay and lends you a false sense of security. Then one day it stops working, and you declare "SCSI voodoo" when what really happened is that it was wrong all along and suddenly the SCSI bus noticed.
Jeff Walther
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