From mboxrd@z Thu Jan 1 00:00:00 1970 From: Richard Scobie Subject: Re: Software RAID when it works and when it doesn't Date: Wed, 17 Oct 2007 11:29:52 +1300 Message-ID: <47153B60.5010008@sauce.co.nz> References: <14526.1192571833@mdt.ecitele.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <14526.1192571833@mdt.ecitele.com> Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids Mike Accetta wrote: > is at the mercy of the low level disk driver. We've observed abysmal > RAID1 recovery times on failing SATA disks because all the time is > being spent in the driver retrying operations which will never succeed. > Also, read errors don't tend to fail the array so when the bad disk is > again accessed for some subsequent read the whole hopeless retry process > begins anew. This is one issue I believe the Western Digital RE/RE2 drives address. The "TLER (time-limited error recovery)" feature limits retrys to try to prevent this. I have the figure of 5 seconds in my head, but could be wrong. Not sure if the Seagate nearline range offers the same sort of thing. Regards, Richard