From: "Keld Jørn Simonsen" <keld@dkuug.dk>
To: ???? ????????? <socketpair@gmail.com>
Cc: linux-raid@vger.kernel.org
Subject: Re: mdadm raid10 performance
Date: Mon, 2 Jun 2008 12:26:19 +0200 [thread overview]
Message-ID: <20080602102619.GA30779@rap.rap.dk> (raw)
In-Reply-To: <b8f627e0806011347x49630976gf9bcf57d7356489b@mail.gmail.com>
On Mon, Jun 02, 2008 at 02:47:53AM +0600, ???? ????????? wrote:
> Hello. I have a simple question.
>
> I just created mdadm raid10 with four disks. The raid build process
> complete successfully.
> All of 4 HDD are connected with separate SATA wires directly to motherboard.
> The mode of operation (selected in bios) neither AHCI nor RAID.
>
> I decide to acheive performance information of software RAID.
> So I read 10 blocks by 64Mb. This give me roughly performance of one disk.
> (I expect that it will be 4x speed ! it should read from 4 hdd
> simultaneously!!!, BUT NOT! )
>
> So, second test were reading 10 blocks (from 0 to 9) in one process,
> and 10 blocks (from 10 to 19) in second thread.
> I acheive performance of half disk... in each thread.
>
> WTF? maybe raid is configured incorrectly ? Or my tests are invalid ?
>
> Any ideas ?
have a look on the howto performance section.
http://linux-raid.osdl.org/index.php/Performance
the far layout is "far" better:-)
Also note the problem solving section there.
doing IO in more threads will have your array behave in random read
mode.
What kernel are you running?
best regards
keld
prev parent reply other threads:[~2008-06-02 10:26 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-06-01 20:47 mdadm raid10 performance Марк Коренберг
2008-06-01 21:22 ` Justin Piszcz
2008-06-02 10:26 ` Keld Jørn Simonsen [this message]
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