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From: mccalpin@vax1.acs.udel.EDU (John D Mccalpin)
Newsgroups: comp.sys.super
Subject: Re: I/O subsystems (was Re: Supercomputer ROI)
Message-ID: <6543@vax1.acs.udel.EDU>
Date: 29 May 90 20:27:49 GMT
Article-I.D.: vax1.6543
References: <359@garth.UUCP> <6374@amelia.nas.nasa.gov>
Reply-To: mccalpin@vax1.udel.edu (John D Mccalpin)
Organization: College of Marine Studies, Univ. of Delaware
Lines: 31

In article <6374@amelia.nas.nasa.gov> yamo@wk46.nas.nasa.gov (Michael Yamasaki) writes:
>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.  [...]

>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?)
>   -Yamo-       yamo@amelia.nas.nasa.gov

Well, I guess I am a bit confused, because 10% of the I/O performance of
a Cray 2 means that your workstation is relatively imbalanced *toward* I/O
performance, rather than away from it!

My Personal Iris runs my 64-bit codes at about 1-2 MFLOPS, which makes it
about 1% of a Y/MP.  The I/O numbers that I have seen are on the order of
1 MB/s, while the Cray numbers are on the order of 10 MB/s to disk -- so I
get about 10% of the Y/MP.
Thus my machine is 10 times more cost-effective for I/O than for
computations!  (relative to a Y/MP).

If you are running scalar codes (yecch!) that are as fast on the
workstation as on the Cray, then this ratio would be turned upside-down.
Perhaps this is the more common occurrence.
-- 
John D. McCalpin                               mccalpin@vax1.udel.edu
Assistant Professor                            mccalpin@delocn.udel.edu
College of Marine Studies, U. Del.             mccalpin@scri1.scri.fsu.edu