Path: utzoo!censor!geac!torsqnt!news-server.csri.toronto.edu!mailrus!ncar!ames!amelia!wk46!yamo
From: yamo@wk46..nas.nasa.gov (Michael Yamasaki)
Newsgroups: comp.sys.super
Subject: I/O subsystems (was Re: Supercomputer ROI)
Message-ID: <6374@amelia.nas.nasa.gov>
Date: 29 May 90 17:57:42 GMT
References: <201@csinc.UUCP> <253@garth.UUCP> <202@csinc.UUCP> <292@garth.UUCP> <10280@batcomputer.tn.cornell.edu> <359@garth.UUCP>
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Reply-To: yamo@wk46.nas.nasa.gov (Michael Yamasaki)
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In article <359@garth.UUCP> fouts@bozeman.ingr.com (Martin Fouts) writes:
>
>One of the ways in which cheap workstations got to be cheap was by
>neglecting to install I/O hardware.  [...]
>
>The single most frustrating thing for me as a consumer of workstations
>is that I/O costs haven't decreased at the same relative rate as MIPS
>and MFLOPS costs --- Although they are decreasing.  [...]

>However, the cost of I/O performance is coming down.  ESDI drives with
>hundreds of megabytes of storage are available on PCS which give the
>same per user performance as the high performance I/O subsystems on
>supercomputers at a lower per user cost, and usually much more storage
>per user.
>

Greetings.  IMHO, one of the places where supercomputers (my only experience
is with Cray 2 and Cray YMP) excel over the touted killer micro solution
is in I/O performance.  In a strange way, it is because of the high cost of
the traditional supercomputer that high cost/high performance I/O subsystems
are acceptable.  Your last statements are (in my experience) dubious.

My workstation (a Personal Iris) gets something less than a megabyte/second
disk I/O.  Our Cray 2 gets something more than 10 megabytes/second.  You
know by the magic of large I/O buffers that it can seem to the user to get
30-40 megabytes/second.  (Wasn't HSP-2's acceptance test something like an
aggregate 100 MBytes/second?)

Even with IPI-2 drives, workstations and PCs will quickly run out of I/O bus
bandwidth.  Add a HPPI or two, support for those million shaded polygons
a second, a few hundred megabytes of memory, multiple micro processors and
uh oh the main bus gets stressed a bit.

There's more to supercomputer architecture than the CPU.  When micros have
sucessfully addressed the rest of the issues, then they'll really be 
"killers".


                                       -Yamo-
                                 yamo@wk46.nas.nasa.gov
                                yamo@amelia.nas.nasa.gov
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(hey, Marty, you gonna show up for some softball one of these days?  -Y-)