Just look at the streaming I/O rate on the DLT7000 drives... I can't
     say about those but the 3590 drives the numbers are like :
     3590 drives are rated at 31 GB/hr
     FWDiffSCSI-2 is 20 MB/sec or 70 GB/hr
     due to the single path nature of SCSI (that is data is written, data
     flow stops and the deviec signals back) you won't see 70 GB/hr data
     transfer...
     We run one 3590 / FWDiffSCSI-2 card (in a pinch we run 2)
     We have seen 28 GB/hr data transfer to a 3590
     Numbers that I've been given are :
        Per FWDiffSCSI-2 card
                1-3590 : 31 GB/hr
                2-3590 : 46.5 GB/hr (31*1.5)
                3-3590 : 54.25 GB/hr (31*1.75)
                4-3590 : 58.125 GB/hr (31*1.875)
     or basically it levels out somewhere around 60 GB/hr and on the
     addition of the 4th you don't really see any additional benefit

     later,
           Dwight



______________________________ Reply Separator _________________________________
Subject: How many drives per SCSI card?
Author:  buechler (buechler AT kcc DOT com) at unix,mime
Date:    8/5/98 11:04 AM


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