It depends on the tape drive type, and the type of SCSI card.

8 bit SCSI I will give you a maximum throughput of about 5MB/s, which would
me saturated with 2 5GB Exabyte tape drives, or 1 DLT or IBM 3570

8 bit SCSI II will give you about 10MB/s
16 bit SCSI II (SCSI Fast/Wide) will give you about 20MB/s
I believe SCSI III (Ultra SCSI) doubles this again, and I believe that there
is now a low
voltage differential Ultra SCSI which is claimed to give 80MB/s throughtput.

Please be aware that the speed of the entire SCSI bus is determined by the
slowest device on the bus, so putting an 8 bit SCSI I device on a 16 bit
SCSI II bus will limit all devices to 5MB/s.

Peter Gathercole
Open Systems Consultant

Buechler, Becky wrote:

> We are about to add another ADSM server on a HPUX 10.2 system. Today we
> have 3 production ADSM servers on MVS.  We plan on using the STK 9710
> tape library. Quantum DLT7000 drives.  We were wondering where the
> dropoff in performance is for how many drives you connect per SCSI card?
> If anyone could share their experiences I would appreciate it very much
> TIA
>
> Becky Buechler
> Kimberly Clark Corporation
> email: buechler AT kcc DOT com