Dual SCSI Hard Drives

Posted on 2006-04-24
Medium Priority
Last Modified: 2010-04-03
I just installed 2 identical SCSI Hard Drives in an old server I'm rehabbing, and I think I might have missed a step in the setup routine, because only one drive is recognised. With both drives connected, my system says one drive is ID 0, and the controller card os ID 7,  but the other drive is missing. If I unplug the ribbon cable from that drive, the other (formerly missing...) Drive appears as ID 0, but the first drive is now missing. What do I need to do to make them both recognised??? I guess this would be like the Master/Slave jumpers in IDE, but how do you arrange dual drives in SCSI? I'm not nearly as proficcient is SCSI as I am in IDE, but M/S doesn't seem to be a SCSI setting. What did I do wrong??


Question by:hubbyatschool
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LVL 97

Accepted Solution

Lee W, MVP earned 200 total points
ID: 16530129
SCSI works by giving each device an unique ID.  You have BOTH hard drives with the SAME ID - this is a no-no.  Set up one drive to be ID 1.  Look at the drive for a block of jumpers, possibly numbered 0,1,2,4 and put the jumper on the set of pins for 1.  Consult your drive's manual or possibly the top of the drive for more information on jumper settings for the hard drives.

Author Comment

ID: 16530197
I KNOW they are the same ID, but I can't find any jumpers on either drive to change it, so apparently ID 0 is the default where no jumpers are installed.

These drives are 8-10 years old, so I don't have any paperwork for them, but I guess I'll search for something online (specs or a manual). I thought there should be jumpers somewhere, but I think IBM must have made them invisible !!!! Good ol' Big Blue!!!

I'll look the drives over some more, and get back to you if I'm still betwixt & bewildered........... THANKS!!!!!!!!
LVL 30

Expert Comment

ID: 16530572
What type of interface ?
SCA(80in),68 pin,or 50 pin?
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LVL 97

Expert Comment

by:Lee W, MVP
ID: 16530610
If they are SCA drives (no obvious power connector) then there are no jumpers - you'd need an SCA adapter with Jumpers OR an SCA backplane in your system.  Otherwise, look underneath the drive for a set of pins, usually quite small ones (not nearly the size of standard jumpers on an IDE hard drive or CDROM).

Author Comment

ID: 16536173
They are not SCA... They are regular 68 pin SCSI, and I think I might have solveds the mystery.....

Apparently, the pins are on the lower front side of the drive, and have been clipped off!!!!!  All that's left is a little nubbin, but there are markings underneath for 0,1,2,4. It looks like someone went crazy with sidecutter pliers, so if I can't get jumpers to make good contact with the (1/32" long) remnants, I guess I can just use them in other units as single drives. Anyway, thanks for all your help, and the education in SCSI technology...
LVL 97

Expert Comment

by:Lee W, MVP
ID: 16536192
No one clipped them.  Some are just very tiny - this is common for SCSI hard drives - you need tiny jumpers

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