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From: bozeman.bozeman.ingr!fouts@unix.sri.com (Martin Fouts)
Newsgroups: comp.os.research
Subject: Re: Extremely Fast File Systems
Message-ID: <5928@darkstar.ucsc.edu>
Date: 10 Aug 90 16:19:30 GMT
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In article <5512@darkstar.ucsc.edu> lm@snafu.Eng.Sun.COM (Larry McVoy) writes:

   In article <5465@darkstar.ucsc.edu> craig@BBN.COM (Craig Partridge) writes:
   >
   >I'm curious.  Has anyone done research on building extremely
   >fast file systems, capable of delivering 1 gigabit or more of data
   >per second from disk into main memory?  I've heard rumors, but no
   >concrete citations.
   >
   >I'm interested because I think we'll need such fast file systems as
   >we build distributed systems over gigabit networks, and I'm somewhat
   >curious to learn what, if anything, has been done so far in this area.

   [Good tecnical shootdown removed.  Summary of removed material:
    It's too expensive/difficult to do with existing technology ]

As part of the contract for the first Cray 2 at NASA Ames, CRI was
required to statisfy a 10mbyte/sec per drive demonstration of a simple
file transfer which copied the entire contents of a source drive to a
destination drive.  They were required to demonstrate 20 simultaneous
transfers (using 40 drives.)  Doing the math, 20x10x8
(instances*rate*bits/byte) = 1.6 Gigabits/second.  They ran that demo
for me at Ames five years ago.  The programs were written in C and
made ordinary read/write calls on files open in ordinary ways. (I've
run the identical source code on a huge number of Unix file systems.)

Tim Hoel et. al. at CRI had designed a fast file system for the Cray
2, which is in production use, and was used for this test.  With a
machine like the 2, the file system required very little cleverness to
pass this test.  Had the test been rewritten to use striping, it could
have been accomplished with a single transfer on a single file system.

BTW, that was a >$20M Cray 2 using fast expensive disk drives.  It was
also running a compute bound workload while running the copy test.

We aren't going to see a Gb/s file system on a PC clone in the near
future, but there are a number of mainframes capable of sufficient
aggrate disk performance now.

We've again reached the point where high performance I/O is a bigger
bottleneck than CPU horsepower.
--
Martin Fouts

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