From: Brad Campbell <brad@fnarfbargle.com>
To: Michele Codutti <codutti@gmail.com>
Cc: linux-raid@vger.kernel.org
Subject: Re: RAID5 alignment issues with 4K/AF drives (WD green ones)
Date: Fri, 30 Dec 2011 14:24:40 +0800 [thread overview]
Message-ID: <4EFD5928.100@fnarfbargle.com> (raw)
In-Reply-To: <A0933627-0D84-496C-B7B7-4FE265C2A212@gmail.com>
On 30/12/11 07:28, Michele Codutti wrote:
> Hi all, I'm writing to this mailing list because I cannot figure out why I had some performance issues with my three WD20EARS (2TB Western Digital "Green" 4K/AF drive).
> These drives has a (sequential) write throughput around 100MB/s. When I combine them in a RAID0 configuration the throughput is around 300 MB/s and in a RAID1 configuration they preserve a single drive performance of 100MB/s.
> When I combine all three drives in a RAID5 configuration the (individual) performance falls around 40MB/s.
> I get the same performance level when I do individual misaligned writes (ex: dd if=/dev/zero bs=6K of=/dev/sda).
> The drives are not partitioned. I'm using the default chunk size (512K) and the default metadata superblock version (1.2).
> I had not formatted the RAID or any single drive during my test i had directly used the raw devices.
> I'm using a 11.10 ubuntu with 3.0.0 linux kernel and 3.1.4 mdadm.
> The hardware is a HP microserver.
>
Just a thought, but do you have the "XP mode" jumper removed on all drives?
Regards,
Brad
next prev parent reply other threads:[~2011-12-30 6:24 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-29 23:28 RAID5 alignment issues with 4K/AF drives (WD green ones) Michele Codutti
2011-12-30 2:00 ` Zdenek Kaspar
2011-12-30 4:48 ` Marcus Sorensen
2011-12-30 4:52 ` Mikael Abrahamsson
2011-12-30 5:45 ` Marcus Sorensen
2011-12-30 6:09 ` Marcus Sorensen
2011-12-31 3:12 ` Mikael Abrahamsson
2011-12-30 6:24 ` Brad Campbell [this message]
2011-12-30 21:04 ` Michele Codutti
2011-12-30 23:17 ` Zdenek Kaspar
2011-12-31 22:20 ` Marcus Sorensen
2011-12-31 15:53 ` John Robinson
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