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To: Julian Elischer <julian@elischer.org>
From: "Poul-Henning Kamp" <phk@phk.freebsd.dk>
In-Reply-To: Your message of "Sat, 30 Jul 2005 12:47:36 PDT."
	<42EBD958.6040402@elischer.org> 
Date: Sat, 30 Jul 2005 22:18:46 +0200
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Cc: FreeBSD Current <freebsd-current@freebsd.org>,
	Brian Candler <B.Candler@pobox.com>
Subject: Re: Apparent strange disk behaviour in 6.0 
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In message <42EBD958.6040402@elischer.org>, Julian Elischer writes:

>> If you know your queue-theory, you also know why busy% is
>> a pointless measurement:  It represents the amount of time
>> where the queue is non-empty.  It doesn't say anything about
>> how quickly the queue drains or fills.
>
>exactly.. I'm trying to work out why teh read and write queues are empty for so 
>much time in a transaction that SHOULD be disk bound....

I am very confident that the disk statistics collected in GEOM don't lie:
your disks are idle because nobody submits I/O requests.

Look at your scheduler...

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.