Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!ames!ames.arc.nasa.gov!lamaster
From: lamaster@ames.arc.nasa.gov (Hugh LaMaster)
Newsgroups: comp.arch
Subject: Re: *big iron*
Message-ID: <32512@ames.arc.nasa.gov>
Date: 25 Sep 89 17:25:22 GMT
References: <21962@cup.portal.com> <1989Sep12.031453.22947@wolves.uucp> <22130@cup.portal.com> <1989Sep16.044013.429@wolves.uucp> <259@ssp1.idca.tds.philips.nl> <22308@cup.portal.com> <7981@cbmvax.UUCP> <11538@burdvax.PRC.Unisys.COM> <22488@cup.portal.com>
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In article <22488@cup.portal.com> cliffhanger@cup.portal.com (Cliff C Heyer) writes:

>To clarify, *big iron* guys emphasize I/O on
>their *mainframes*, but not on their *PCs*. Instead, they emphasize

>This is the only answer I can come up with to explain why IBM 
>consistently puts out PCs that are substantially below average in "real"
>disk I/O speed: 200KB/sec. Just look at Byte benchmarks. Plus I'm

>So my belief is that some companies are trying to save I/O BW for their
>*big iron* by purposefully handicapping the speed of their PCs. They 

Many of your points are well taken.  In fact, many big companies don't make it
a secret that they limit their user's options to force certain migration paths.
The industry trade rags are full of speculation about such things, and 
sometimes even print a lot of criticism of the big boys for introducing
new, high performance products too quickly - it is hard on the used equip. mkt.

However, I think you are painting with too broad a brush to include Sun, MIPSCo,
etc. in your list.  Remember that the controllers you have been using for
your comparisons to get ~1 MB/sec. through a filesystem are relatively new.
Most of these controllers have been thoroughly *debugged* and in volume
production (two prerequisites for full service companies to buy) for 6 mos.
to one year.  Sun now sells faster controllers that will do almost 1 MB/sec.
on SMD disks through a Unix filesystem.  I haven't had a chance to measure
any IPI or synchronous SCSI disks.  But it is unfair to use today's controllers
to criticize systems shipped 1-2 years ago.

The other thing that would probably help would be if more people said to
salesrep from company X:  "I am buying the system from company Y.  Even
though the CPU is only 10 MIPS instead of 20, it can stream data from 4
controllers simultaneously at 2.5MB/sec. each, with negligible CPU overhead."

  Hugh LaMaster, m/s 233-9,  UUCP ames!lamaster
  NASA Ames Research Center  ARPA lamaster@ames.arc.nasa.gov
  Moffett Field, CA 94035     
  Phone:  (415)694-6117