Date: Fri, 25 Dec 2009 18:19:01 +0000 From: "Poul-Henning Kamp" <phk@phk.freebsd.dk> To: Alexander Motin <mav@FreeBSD.org> Cc: FreeBSD-Current <freebsd-current@FreeBSD.org>, freebsd-arch@FreeBSD.org Subject: Re: File system blocks alignment Message-ID: <28375.1261765141@critter.freebsd.dk> In-Reply-To: Your message of "Fri, 25 Dec 2009 16:03:05 %2B0200." <4B34C619.7070505@FreeBSD.org>
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In message <4B34C619.7070505@FreeBSD.org>, Alexander Motin writes: >Poul-Henning Kamp wrote: >- Second is a row size - stripe size * number of data disks. You may >freely read less information then full row, but short write cause RAID >to handle read-modify-write scenario. There is a far worse scenario: a stripe-spanning write, it forces a RMW cycle over two different RAID5 stripes. -- 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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