From mboxrd@z Thu Jan  1 00:00:00 1970
From: Richard Scobie <richard@sauce.co.nz>
Subject: Re: software raid rebuilding and O_DIRECT access (xfs_repair) slowness
Date: Fri, 02 Oct 2009 07:30:41 +1300
Message-ID: <4AC4F551.2080606@sauce.co.nz>
References: <200910011949.42542.a.miskiewicz@gmail.com>
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To: Arkadiusz Miskiewicz <a.miskiewicz@gmail.com>, Linux RAID Mailing List <linux-raid@vger.kernel.org>
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Arkadiusz Miskiewicz wrote:

> The question is now why software raid is soo slow when device is accessed with 
> O_DIRECT by xfs_repair? (that's hch guess on what's the problem). Is this bug, 
> expected behaviour?

I would think that this is not unexpected - 2 disk bound tasks, one 
(resync), which requires the heads to sequentially step cylinder by 
cylinder from the beginning to the end.

The other, xfs_repair, which is randomly seeking all heads all over the 
platters.

Regards,

Richard