From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kay Diederichs Subject: Re: Raid1: sdb has a lot mor work then sda Date: Wed, 25 Apr 2012 09:47:52 +0200 Message-ID: <4F97AC28.7060609@uni-konstanz.de> References: <4F96BCC9.9080003@marco.de> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4F96BCC9.9080003@marco.de> Sender: linux-raid-owner@vger.kernel.org Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids On 04/24/2012 04:46 PM, Daniel Spannbauer wrote: > Hello, > > at the moment I'm trying to find a bottleneck on my lamp-server with > opensuse 11.4 (Kernel 2.6.37.6) > > Sometimes the system has a very poor performance because of a high io-wait. > If I watch the systems disk-access with "atop -dD" I can see that sda is > the most of the time at a load of 10%, sdb sometimes is at 100% or > higher at the same time. > > In my opinion in a Raid1-System both disk should have nearly the same load. > > Or may I wrong whis this? > > Both harddisks where changed 3 Weeks ago, /proc/mdstat shows that the > rebuild was successfull and the array is functional. Today I've changed > th SATA-Cable and the Port on the Maindboard of sdb, but the behaviour > is still the same. Both disks passed the extended smart-self-test. > > Any ideas about that? > > Regards > > Daniel Are the disks more or less the same in all SMART attributes (from smartctl -a)? I have seen such a behaviour in the case of one disk being marginal, and/or having a couple of bad spots which need several trials to be read. This always also resulted in longer "smartctl -t long" times than usual, but did not always show up clearly in the SMART output (or I looked at the wrong attributes). I'd try to exchange the disk. HTH, Kay