Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!mit-eddie!uw-beaver!milton!seymour
From: seymour@milton.acs.washington.edu (Richard Seymour)
Newsgroups: comp.sys.dec
Subject: One controller or two???
Message-ID: <567@milton.acs.washington.edu>
Date: 24 Oct 89 01:47:54 GMT
Reply-To: seymour@milton.acs.washington.edu (Richard Seymour)
Distribution: comp
Organization: University of Washington, Seattle
Lines: 20

Which would be better/faster/whatever :
 we start with :
  a KDA-50 on a Qbus VAXstation 3200 with an ra-81 
We want to add a spindle:
Choose between: adding a 3rd party  DSI-compatible drive (i.e. hangs
 on the RA-81's cables like another RA-8x) for $6500
  -- or --
an entire second system:  Qbus MSCP-compatible 3rd party controller
  with ESDI drive (price about $5000).
Assume Both options use the same 760 megabyte drive, both with ESDI.

does the KDA-50 handle bus contention better because it knows everything
that's happening? or are two controllers better than one?
(the second controller can be purchased  with from zero to 1Megabyte 
 of cache -- i just analyzed a 6-month system which showed only a 10%
 hit rate in a 1Mbyte cache)

please e-mail and i'll summarize.
-- dick  seymour@uwaphast.bitnet     seymour@phast.phys.washington.edu
206-543-4298  (salespeople welcome to call)