>Any performance gained using a PCI mboard and PCI disk controller
>verses an EISA system with lets say Adaptec 1742's and 1740's
>And included in this mix, three disk controllers 18 to 21 SCSI-2 drives, 
>boxes of SIMMS ?

Bottom line is that either one will do the job, since both will give
you busmaster with 32-bit addressing and burst mode.  If you are going
to saturate each controller that heavily, though, PCI will probably
give you small performance boost over EISA.  Neither will completely
saturate the bus however (3 * 10MB/s (SCSI2) < 33MB/s (EISA)),
although PCI will have more headroom (133MB/s).  You might also think
about going wide SCSI if you're going with that many drives per
controller.  In that case PCI would be a definite advantage (3 *
20MB/s (SCSI2-Wide) > 33MB/s (EISA) < 133MB/s (PCI)).

Recommended controllers are:

BusLogic BT747 (SCSI2 EISA)
         BT757 (SCSI2 WIDE EISA)
         BT946 (SCSI2 PCI)
         BT956 (SCSI2 WIDE PCI)

The newer Adaptec boards are also rumored to be supported now, though
I don't know how heavily that has been tested.  And, the NCR 83c510
(SCSI2) and 83c525 (SCSI2 WIDE) are also supported, though some people
have reported flakiness with that driver.

-----------------------------------------------------------------------------
  Michael L. VanLoon                                 michaelv@HeadCandy.com
       --<  Free your mind and your machine -- NetBSD free un*x  >--
     NetBSD working ports: 386+PC, Mac 68k, Amiga, HP300, Sun3, Sun4,
                           DEC PMAX (MIPS), DEC Alpha, PC532
     NetBSD ports in progress: VAX, Atari 68k, others...
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