What happens when a SCSI hard drive is not correctly terminated?

[beer]

We have been having problems with an NT server after we pulled the second hard drive out. Both hard drives are LVD SCSI, a 9 GB Quantum Atlas 10K, and a 9 GB Seagate. The seagate was the default drive and the Atlas was put in there to get some data off it. We pulled the Atlas out and it booted but the event log was full of warnings. I mean if you cleaned the event log out within seconds it would be full again with these warnings. When we rebooted, now we're getting an inaccesable boot device BSOD on load. Could a termination issue be the problem?

The Seagate is currently sitting on an Adaptec 2890 (I believe) controller at SCSI ID 0. A CD ROM resides on an 2880 secondary controller at SCSI ID 5 or so.

 

[Hanpan]

Generally termination helps preserve signla intergrity. IT is not absolutely necessary but you will get a lot of data errors /corruption if it is not properly termanated. Maybe the drive has gone south???

 

[beer]

How would I go about termination of the signal cable? Would I terminate the chain on the drive or on the cable?

There are two devices on the SCSI chain. SCSI ID 0 is the Seagate drive. SCSI ID 7 is the SCSI controller.

I know the drive is working fine, it was working yesterday perfectly. I messed around and got the Quantum in there, and I pull it out, and it's giving me these errors.

I have NO experience with SCSI at all. I'm at a complete loss.

 

[bacillus]

<< How would I go about termination of the signal cable? Would I terminate the chain on the drive or on the cable? >>


you'll have to have the terminator at the end of the lvd cable ie active termination.
the lvd hdds don't have a termination jumper on the back!
the lvd hdds usually come unjumpered (=ID0). have you assigned anID for the second hdd by jumpering it otherwise you'll have 2 hdds on the cable with the same ID of 0 leading to errors!

 

[Topochicho]

most of time, the termination is done on the drive itself. Although there are exceptions, my scsi jazz drive came with a terminator that you plug directly into the scsi cable at the end.

your original drive would have been (probably)configured to be device 0 and have the termination set if it was installed solo. you need to unterminate it and terminate the new drive and set that to one of the remaining 6 devices.

I think the last device on the chain has to be terminated, but the last device does not have to be the lowest device number... if thats right then you could connect the original drive farther down the chain, and then connect the new drive in before, and not have to fool with terminations....

 

[dkozloski]

LVD drives have no provisions for termination except that some have jumpers that force single-ended operation. If you have no external devices you can be pretty sure that the controller end of the chain is automatically terminated correctly by the controller. The last device on the other end of the chain must be an external termination. Usually the cable will have two plugs on the end that are very close together. the last takes the termination module and the other is for a device. Termination power is usually supplied by the controller so that is not an issue. The devices do not have to be in ID order number on the cable; as long as there are no ID duplications you should be good to go.

 

[beer]

Is the standard termination module resemble a block, located on the last SCSI connector? I want to make sure I'm terminating this right.

 

[Tako]

I think your problem is related to drive letter assignment. Say your Segate drive was assigned a C: but as soon as you plug in the Atlas drive it may have &quot;shifted.&quot; Perhaps your Atlas took over the C: drive now and the Seagate drive was pushed off and assigned a drive letter D. This WILL definitely cause problem. At least my Win2K hated it.

Tako_chu

 

[dkozloski]

The termination module looks like it's about Zippo lighter size and black. The designated boot drive as specified in the controller setup is usually the C: drive. By default the lowest SCSI ID# drive is the boot drive if no other is selected.

 

[beer]

hey guys I got it fixed. It turns out that there was a jumper about 1.5 mm long (realllllly small) that was put back on backwards. I may have accidently taken it off and put it back on the wrong way. Anyways I oriented it right and it's working.

 

[dkozloski]

Good work!