Tape Drive/Disk System Daisy Chain

[Joseph C. Denman]

Hi All,

I need a little help getting this L1000 to recognize a tape and disk system when daisy chained.

1. L1000
2. Tape Drive (surestore Dat 40)
3. Disk system (HP Disk System 2100)

I just set up a new system that only has the one single end scsi off the network card. When I plug the individual devices into the card, the system sees them. However, when I dasiy chain them, it does not see either???? What I mean by see is that I am stoping the boot sequence and typing sea at the menu. I have used this configuration before with the same products and it has worked fine. In fact, I pulled the cable I am using to daisy chain, off anther system that was in the same configuration. I have tried replacing the terminator but no help.

Does any know what could be wrong? Does the tape drive have to be first in the chain? The Disk system has an A,B,C switch in the back. It is set on B. Does that have anything to do with it?

Any help would be appreciated.

Thanks,

...jcd...

[A. Clay Stephenson · Accepted solution]

This is the classic symptom of duplicate SCSI ID's on the same bus. If you will do an ioscan -fn with thye tape drive connected and then an ioscan -fn with the drive encolure connected, I think you will spot the conflict. The system doesn't care where the tape drive is physically located.

The other thing that can cause this is improper termination. For example, if the tape drive had termination enabled then it MUST be on the end of the bus. There must be exactly two terminators on a bus and they must be located on each physicalk end of the bus. Typically the controller (almost always set to SCSI ID 7) has termination enabled and the other termination is on the last device in the chain.

[Pete Randall]

Sounds like a conflicting SCSI ID.


Pete

[Chris Vail]

Like the others have said, its probably a duplicate SCSI id setting.

What you're doing is not a terribly good idea. It can be done, but your tape will slow down your disks, and your disks will slow down your tape. If you can, dedicate one SCSI channel to tape and another to disk.

Chris

[TwoProc]

I also vote for the SCSI ID problem. I've also seen it with termination. I've got one more thing that I've seen it for, and that's a bad/marginal power supply in one of the units. Individually, either device would work, but together they failed. Checked the power supplies on both units with a meter and found one was generating 1/2 voltage on one of the power lines into the unit. Replacing the power supply fixed the problem. Rare, but I put it as the third thing I check when having this type of trouble.

[Naveej.K.A]

Hi,

I agree with all that this could be a genuine SCSI ID conflict issue and if you connect in this manner, it is going to slow down the data transfer between your server and DS2100. The switch behind is used to select the SCSI ID (ABC switch).

I would recommend you to change the SCSI ID of the Tape drive. This can also be changed with the help of a switch behind the drive.

Cheers!!
Naveej

[Joseph C. Denman]

Thanks for the responses. The server is off-site and I can't get to it today. Hopefully I will get to it tomorrow. I will let ya'll know.

...jcd...

[Joseph C. Denman]

Closing Thread. SCSI ID Issue.