Date: Mon, 02 May 2005 15:15:06 +0200 From: "Poul-Henning Kamp" <phk@phk.freebsd.dk> To: Eric Anderson <anderson@centtech.com> Cc: =?ISO-8859-15?Q?=22Arne_=5C=22W=F6rner=5C=22=22?= <arne_woerner@yahoo.com> Subject: Re: Very low disk performance on 5.x Message-ID: <17442.1115039706@critter.freebsd.dk> In-Reply-To: Your message of "Mon, 02 May 2005 08:10:52 CDT." <427626DC.5030702@centtech.com>
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In message <427626DC.5030702@centtech.com>, Eric Anderson writes: >Don't mean to be terse here, but I'm talking about the same test done an >two different RAID5 configurations, with different disks, and not just >me - other users in this very thread see the same issue.. Uhm, if you are using RAID5 and your requests are not aligned and sized after the RAID5 you should *expect* read performance to be poor. If you your request ends up accessing two different blocks even just once per stripe, this totally kills performance. -- 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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