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Path: utzoo!henry
From: henry@utzoo.UUCP (Henry Spencer)
Newsgroups: comp.arch
Subject: Re: disk performance benchmarks.
Message-ID: <7759@utzoo.UUCP>
Date: Tue, 10-Mar-87 17:11:17 EST
Article-I.D.: utzoo.7759
Posted: Tue Mar 10 17:11:17 1987
Date-Received: Tue, 10-Mar-87 17:11:17 EST
References: <307@sunlamp.UUCP>
Organization: U of Toronto Zoology
Lines: 19

> What I'm looking for (golden fleece) is a reasonably fair set of general
> disk performance metrics...

A general comment:  the nature of those metrics will depend heavily on
what you intend to use the disks for.  In particular, the nature of the
computing environment will make a big difference.  Is it a single-user
machine, or a timesharing system / file server?

As an example of how these things can affect results, notice that the
pre-4.2 benchmarks, demonstrating how wonderful the 4.2 file system was,
were all run SINGLE USER.  There is a conjecture hereabouts -- not verified
by experiment, mind you -- that on a busy multi-user system, the increase
in block size accounts for 100% of the performance improvement, with things
like cylinder groups contributing absolutely nothing.  (What does it matter
if all the blocks of your file are on the same cylinder?  The heads won't
stick around anyway, they've got other customers to service.)
-- 
"We must choose: the stars or	Henry Spencer @ U of Toronto Zoology
the dust.  Which shall it be?"	{allegra,ihnp4,decvax,pyramid}!utzoo!henry