From: Michal Soltys <soltys@ziu.info>
To: thomas62186218@aol.com
Cc: mauermann@gmail.com, keld@dkuug.dk, linux-raid@vger.kernel.org
Subject: Re: LVM on raid10,f2 performance issues
Date: Mon, 19 Jan 2009 08:30:22 +0100 [thread overview]
Message-ID: <49742C0E.6080402@ziu.info> (raw)
In-Reply-To: <8CB47EBD70FE9E8-AC4-981@WEBMAIL-DG06.sim.aol.com>
thomas62186218@aol.com wrote:
> Hi everyone,
>
> I too was seeing miserable read-performance with LVM2 volumes on top of
> md RAID 10's on my Ubuntu 8.04 64-bit machine. My RAID 10 has 12 x 300GB
> 15K SAS drives on a 4-port LSI PCIe SAS controller.
>
> I use:
> blockdev --setra 65536 /dev/md0
>
> And this dramatically increased my RAID 10 read performance.
>
> You MUST do the same for your LVM2 volumes for them to see a comparable
> performance boost.
>
> blockdev --setra 65536 /dev/mapper/raid10-testvol
>
> Otherwise, your LVM will default to 256 read-ahead value, which stinks.
> I increased my read performance by 3.5x with this one change! See below:
>
Yea, that's the general idea, besides proper alignment. It wokred nice
for Holger as well. Specifying (popular for some reason) 65536 is quite
an overkill though, imho.
next prev parent reply other threads:[~2009-01-19 7:30 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-12-01 0:00 LVM on raid10,f2 performance issues Holger Mauermann
2008-12-01 16:42 ` Keld Jørn Simonsen
2008-12-02 23:28 ` Holger Mauermann
2008-12-03 7:15 ` Keld Jørn Simonsen
2008-12-03 9:43 ` Michal Soltys
2009-01-19 1:24 ` thomas62186218
2009-01-19 7:28 ` Peter Rabbitson
2009-01-26 19:06 ` Bill Davidsen
2009-01-19 7:30 ` Michal Soltys [this message]
2009-01-19 12:17 ` Keld Jørn Simonsen
2009-01-19 12:24 ` Peter Rabbitson
2009-01-19 13:59 ` Keld Jørn Simonsen
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