Path: utzoo!attcan!uunet!aplcen!samsung!rex!ames!amelia!wk46!yamo
From: yamo@wk46..nas.nasa.gov (Michael Yamasaki)
Newsgroups: comp.sys.super
Subject: Re: I/O subsystems (was Re: Supercomputer ROI)
Message-ID: <6390@amelia.nas.nasa.gov>
Date: 30 May 90 16:26:31 GMT
References: <359@garth.UUCP> <6374@amelia.nas.nasa.gov> <6543@vax1.acs.udel.EDU>
Sender: news@amelia.nas.nasa.gov
Reply-To: yamo@wk46.nas.nasa.gov (Michael Yamasaki)
Organization: NASA Ames Research Center
Lines: 31

In article <6543@vax1.acs.udel.EDU> mccalpin@vax1.udel.edu (John D Mccalpin) writes:
>
>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).
>

I didn't intend to say that the Cray's were well balanced flops to I/O.
Some people like to think Crays turn compute bound problems into 
I/O bound problems.  Uh, I shudder to think what using an Iris with 
10% of it's current I/O bandwidth would be like.  

(Cost effective?  If it takes me the same time to do 10% of a problem, it 
wouldn't seem to be cost effective to me. ;-)

The Cray numbers, by the way, are what a typical user might expect for a
single processor job with 50 or so other users.  The Iris numbers are of
course for a single user.


                                       -Yamo-
                                 yamo@wk46.nas.nasa.gov
                                yamo@amelia.nas.nasa.gov
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