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Date:      Fri, 31 Jan 2003 20:58:27 +0100
From:      phk@freebsd.org
To:        Julian Elischer <julian@elischer.org>
Cc:        Steve Byan <stephen_byan@maxtor.com>, freebsd-fs@freebsd.org, tech-kern@netbsd.org
Subject:   Re: DEV_B_SIZE 
Message-ID:  <31671.1044043107@critter.freebsd.dk>
In-Reply-To: Your message of "Fri, 31 Jan 2003 11:48:56 PST." <Pine.BSF.4.21.0301311144370.45015-100000@InterJet.elischer.org> 

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In message <Pine.BSF.4.21.0301311144370.45015-100000@InterJet.elischer.org>, Ju
lian Elischer writes:
>
>
>One thign I thought of is that it is not uncommon to 'dd' an entire
>filesystem from one partition to another.
>If we create a filesystem that is 'aligned' and we copy it to be 
>'unalligned', we'd have a sudden performance drop for no immediatly
>obvious reason. What was one write, would become a 2-sector read,
>modify and 2-sector write. Especially when copying from one failing
>drive to another with slightly different characteristics.

If you run dd without bs=ALOT you deserve bad throughput.

-- 
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.

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