There are multiple kinds of 68-50 pin adapters. The external 68-50 pin adapter you need must terminate the upper bits on the SCSI bus. Most 68 to 50 adapter cables simply leave the unused wires unconnected. (Your internal 68-50 pin adapters probably do this.) Larry Pete Flugstad writes: > Greetings all, > > This is technically not a Linux specific question, more along the > lines of Ultra SCSI. But I'm hoping someone will have a quick > answer for me anyway. > > I've got a Symbios 8751SP SCSI controller (53C825 based) - it's > Ultra-Wide. I've got the following setup internally: > > + Controller (ID 7) > +--- unused connection > +--- unused connection > +--- HP 1.1 GB HD (Fast - Narrow - ID 1) > +--- Sony CDU-76S 4x CD-ROM (Slow - Narrow - ID 6) > +--- unused connection > +--- Quantum Viking 4.5 GB HD (Ultra - Wide - ID 0) > Termination Enabled - Term Power enabled > > For the Narrow devices, I have 68-50 pin adaptors. > > Now, this all boots and runs just fine. I have the Quantum running > at 40 MB/s - the HP is at 10 MB/s and the Sony is at 5 MB/s - all as > expected. The HP does NOT have Term Enabled, and I've removed the > resistor blocks from the Sony (I assume that's correct, as I don't > have and can't find online any docs for the Sony). > > Now, however, I'm trying to connect a Jaz 2GB drive (Ultra - Narrow - > ID3) to the external connector, and it's giving me lots of grief. > When I first tried this, I couldn't even get LILO to come up. Then > I removed the narrow devices from the internal chain, and I could > boot, but loading the kernel had a number of timeouts and other > problems. Despite that I was able to boot fully - and shutdown > right away again... > > Finally, I jacked the Quantum down to 20 MB/s, (using the Symbios > BIOS setup), things got better, and I could connect the other internal > devices. But it's still having occasional timeout problems - say > one ever 5 to 10 minutes, depending on how heavily I use thing. > And they are all still on ID 0 (the end of the chain). This causes > the controller to reset the bus, which basically lock severything > up for 5-10 seconds. Needless to say, I'm not very comfortable with > this. > > Now, the external cable is fairly high quality - cablestogo.com, > part # 08252 - SCSI MD68M - MD50M. It fits nice and tight. The > internal cable also seems of reasonable quality; it's a 7 device > cable I got from oscarno1.com. The 68-50 pin adaptors also seem > reasonable quality - oscarno1.com again. I have the Jaz setup > with Term enabled (rather than their Auto setting). > > The internal cable is probably about 1 meter. The external cable > is about 3 feet. Could the length of the chain be causing me > problems? I've seen references that indicate that the total SCSI > length should be less than 1.5M for Ultra - I guess I'm exceeding > that slightly. Would moving all the internal devices closer to > the controller work. Are there any issues with the dangling cable > out there? Should I get a smaller (4-device) cable? > > I've tried all kinds of things to try and get this to work, > but I haven't had any luck. I really want to get things working > reliably at their correct speeds. Any suggestions would be > greatly appreciated. I'm already toying with replacing the > CD-ROM, since it's the only slow device, but I don't think that > will help much. > > Thanks, > Pete > > - > To unsubscribe from this list: send the line "unsubscribe linux-scsi" in > the body of a message to [EMAIL PROTECTED] - To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to [EMAIL PROTECTED]
