From owner-freebsd-questions  Thu Apr 22 15:53: 5 1999
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From: Mikhail Teterin <mi@misha.cisco.com>
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Subject: Re: writing slower with SoftUpdates
In-Reply-To: <19990422174301.B51036@dan.emsphone.com> from Dan Nelson at "Apr 22, 1999 05:43:02 pm"
To: dnelson@emsphone.com (Dan Nelson)
Date: Thu, 22 Apr 1999 18:49:36 -0400 (EDT)
Cc: gjohnson@nola.srrc.usda.gov, questions@FreeBSD.ORG
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Dan Nelson once wrote:

> In the last episode (Apr 22), Glenn Johnson said:
> > Interesting! I ran your script and found all three of my SCSI drives
> > had write caching enabled. Is it the same situation with IDE drives
> > and softupdates with regards to performance degradation?
 
> Most IDE drives don't even support command queueing and have such
> small internal buffers compared to equivalent SCSI drives (i.e. IBM's
> Deskstar 16gb IDE has a 512k cache, while the Ultrastar 18gb SCSI has
> a 2MB cache), so you're not going to see much of a decrease because of
> the write cache.

It is surprising, nothing in FreeBSD tries to take advantage of this
huge caches... My first computer only had 128Kb of RAM in it...

	-mi


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