From: "Keld Jørn Simonsen" <keld@dkuug.dk>
To: Holger Mauermann <mauermann@gmail.com>
Cc: linux-raid@vger.kernel.org
Subject: Re: LVM on raid10,f2 performance issues
Date: Mon, 1 Dec 2008 17:42:45 +0100 [thread overview]
Message-ID: <20081201164244.GB23899@rap.rap.dk> (raw)
In-Reply-To: <49332920.5010503@gmail.com>
On Mon, Dec 01, 2008 at 01:00:32AM +0100, Holger Mauermann wrote:
> When I setup LVM on top of a 4 disk RAID 10 with f2 layout read/write
> performance is really worse - it's far below single drive speed...
How is it if you use the raid10,f2 without lvm?
What are the numbers?
Did you use it with a live file system, or with just the raw raid?
Live fs performance is much better than raw fs, in practice the raw fs
performance is not really related to real life for raid10,f2.
This because the elevator enhances operation quite a lot.
best regards
keld
> I did some testing with dd and hexdump and I noticed that after writing
> a 128k file (with 64k "X" and 64k "Y") to the lvol the data on the raw
> disks looks somewhat weird:
>
> sda: sdb: sdc: sdd:
> ----------------------
> YYYY .... .... XXXX
> .... .... .... ....
> XXXX YYYY .... ....
> .... .... .... ....
>
> Any hints how to tune this? With LVM on a standard RAID 10 (n2) the data
> appears as expected on the disks:
>
> sda: sdb: sdc: sdd:
> ----------------------
> YYYY YYYY XXXX XXXX
> .... .... .... ....
> .... .... .... ....
> .... .... .... ....
>
>
> --
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next prev parent reply other threads:[~2008-12-01 16:42 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 [this message]
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
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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