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SCSI Tape drive problem

Ayman Altounji
Valued Contributor

SCSI Tape drive problem

I have a customer that tries to make a Tandberg SLR100 SCSI drive to run on a DL380. However, it appears that the drive is reset shortly after a backup is started (1 GB into the backup). The latest drives are used: CPQ32FS2.SYS Version: 5.4.10.0. Any idea what's going on?
2 REPLIES
Ayman Altounji
Valued Contributor

Re: SCSI Tape drive problem

Compaq Engineering has not tested the Tandberg SLR100 SCSI tape drive on any model of Compaq server, so we have no compatibility or installation information available. Which SCSI controller is the tape connected to? Does the tape drive have a 50 pin or 68 pin SCSI connection? If you are mixing a SCSI-2 tape drive and Ultra SCSI hard drives on the same SCSI bus, you can get an error generated from the slower tape drive when the tape drive is first accessed by a backup program or during the system bootup.

This is because the system boots with the SCSI bus set to the faster mode. When the SCSI controller tries to detect and communicate with the slower tape device, the SCSI bus times out because it can not communicate with the tape drive at the faster SCSI bus speed. This generates the error message. The SCSI bus then changes to the slower speed and then the tape drive can be detected. This is the normal operation of the SCSI bus when mixing SCSI devices of different types. Your backup program must allow for the SCSI bus speed change. Older backup programs do not wait for the but to be set to the slower speed. During the SCSI bus speed change, the tape drive is unavilable. If the backup software tries to communicate with the tape drive during the SCSI bus speed change, errors will be generated.

To keep from getting the error messages and for faster backup performance, put the SCSI tape drive on a deadicated SCSI controller. Then the SCSI bus does not have to change speed when the tape drive is accessed. You also get better backup performance, because one SCSI controller is reading information from the hard drives, while the other SCSI controller is writing to the tape drive.
Ayman Altounji
Valued Contributor

Re: SCSI Tape drive problem

Addendum to Compaq reply. Remember under all circumstances that the bus is Ultra even if the tape drive isn't. DO NOT use the tape drives internal terminator, buy a good active terminator (try Granite Digital, www.scsipro.com for one) as glitching the bus will cause this. Also remember that you must use Teflon controlled impedence flat cables with Ultra buses, that old PVC junk will not work.