From: Tomasz Chmielewski <mangoo@wpkg.org>
To: Jon Nelson <jnelson-linux-raid@jamponi.net>
Cc: Linux-Raid <linux-raid@vger.kernel.org>
Subject: Re: Awful Raid10,f2 performance
Date: Mon, 02 Jun 2008 16:53:07 +0200 [thread overview]
Message-ID: <48440953.3040004@wpkg.org> (raw)
In-Reply-To: <cccedfc60806020711o39ccd321h5e410c963d8bf3b1@mail.gmail.com>
Jon Nelson schrieb:
> I have set up a 3-disk raid10 using f2 layout using 3x SATA disks each
> capable of 70+ MB/s (give or take).
> The CPU is a dual core 64 bit Athlon 3600+, and the SATA interface
> consists of NVidia MCP55+ (PCIe or whatever).
> Previously this was a 3 disk raid5.
> The problem: I'm getting really awful transfer rates. 7-9MB/s
> per-drive with 21-30MB/s combined. The average hangs around 22-24MB/s.
> This, I feel, is really awful!
>
> What parameters can I twiddle to improve the performance?
> I am not using NCQ.
> The drives individually are capable of 70+ MB/s.
> I am using the deadline I/O scheduler but I have tried the others.
> This is the openSUSE 2.6.22.17 kernel.
> I am getting the I/O rates via dstat.
> I am using the jfs filesystem primarily.
> The operation I am performing varies but the I/O rates don't (much).
> In particular, moving one 17G file from a logical volume (I am using
> LVM) to another, both filesytems are JFS.
> The load is around 2.6, with these four processing being the top CPU
> consumers (they wiggle around a bit):
>
>
> 2034 root 10 -5 0 0 0 D 10 0.0 201:00.30 md0_raid10
> 10631 root 18 0 8436 1076 668 D 7 0.1 2:07.65 mv
> 218 root 15 0 0 0 0 D 3 0.0 2:06.30 pdflush
> 2182 root 10 -5 0 0 0 S 3 0.0 0:32.51 jfsCommit
>
> Is there more information that I can provide that can help explain why
> I'm getting such slow speeds?
It would be interesting to know the raw values of your RAID-10 (without
any filesystem).
I.e.
# dd if=/dev/zero of=/dev/md10 bs=64k count=10000
# echo 3 > /proc/sys/vm/drop_caches
# dd if=/dev/md10 of=/dev/null bs=64k
--
Tomasz Chmielewski
http://wpkg.org
next prev parent reply other threads:[~2008-06-02 14:53 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-06-02 14:11 Awful Raid10,f2 performance Jon Nelson
2008-06-02 14:53 ` Tomasz Chmielewski [this message]
2008-06-02 15:09 ` Jon Nelson
2008-06-02 18:30 ` Keld Jørn Simonsen
2008-12-15 13:33 ` Jon Nelson
2008-12-15 21:38 ` Neil Brown
2008-12-16 2:47 ` Jon Nelson
2008-12-16 4:03 ` Keld Jørn Simonsen
2008-12-16 4:28 ` Jon Nelson
2008-12-16 10:10 ` Keld Jørn Simonsen
2008-12-16 15:26 ` Jon Nelson
2008-12-16 15:53 ` Jon Nelson
2008-12-16 22:01 ` Keld Jørn Simonsen
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