Re: Very low disk performance on 5.x

From: Poul-Henning Kamp (phk_at_phk.freebsd.dk)
Date: 05/02/05

  • Next message: Eric Anderson: "Re: Very low disk performance on 5.x" 
    To: Eric Anderson <anderson@centtech.com>
Date: Mon, 02 May 2005 15:15:06 +0200

    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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  • Next message: Eric Anderson: "Re: Very low disk performance on 5.x"

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