SCSI boffins needed, PC question

[lorddef]

Okay peeps I need a scsi know-it-all to put me straight.

I have 3 Ultra2 SCSI discs, and an Adaptec Ultra2 LVD SCSI controller. Now my problem is that I don't know what cable to buy, basically I need a 68pin cable and a terminator, but are lvd/ultra2 cables and terminators different to standard wide 68pin scsi cables and terminators?

I've seen some ul;tra2 cables on ebay, and they ain't exactly cheap, I've also seen them on dabs.com, and well... just a little pricey  :-)

[lorddef]

Oh yeah, and I mean I want it to run at full speed, not just use a cable that will work but one that will run at ultra2/lvd...

[Merc]

Well I'm certainly not an expert, but I went through this a while ago setting up a couple of U160 drives.  From what I remember, you do need specific LVD cables and terminators.

The LVD cable you need is like a normal flat cable, but some of the lines are twisted with each other along the length of the cable.  This is done to cut down on crosstalk as I recall.  Something about lower voltages and higher speeds requiring less interference.  The cable I got had a terminator built into one end, so there were no worries about having the wrong terminator.


Hope this helps!

[Seehund]

SCSI FAQ & Glossary

Read more here, check out the "SCSI Information" links at the bottom.

As far as I know, Ultra2 is LVD (or HVD, or LVD/MSE...). Sure you don't mean "Ultra SCSI-2" (which is 50-pin)?
Yes, they do everything to confuse us, don't they?

Ultra2/LVD is (like everything SCSI) backwards compatible, but to me it seems like you don't even have to worry about that. Get a 68-pin cable rated for at least Ultra2, Ultra160, Ultra320 or FAST-40 (heck, they might even call it SCSI-3). Sometimes they come with premounted LVD (or HVD, or LVD/MSE - check this in those FAQs) terminators.

What's the name(s)/model(s) of your disks? The controller?

[billchase]

If you have access to a regular 68pin cable, I would
try that first.  I know it works fine for UltraSCSI (40 MB/s).
The twisted cable would be the safer choice, but more expensive.

C Snyder

[Wain]

It really is recommended to use Ultra2 cables, they're expensive, but they've been made to support extremely high discharge times without crosstalk that standard
ribbon cables can't handle.

[lorddef]

The adaptor is an adaptec 2940U2W LVD adaptor, and the disks are Compaq (rebranded Segates) Ultra2/LVD disks.

Cheers for all the advice though peeps. Still waiting for the card as I got it off ebay, the guy says he'll throw in a cable so I'll see what that's like. I'm sure the 68pin cable in another box of mine looks pretty nifty though, so I can always try that too.