From mboxrd@z Thu Jan 1 00:00:00 1970 From: Max Eaves Subject: Re: Problems with RAID 6 across 15 disks Date: Thu, 01 Apr 2010 15:07:27 +0100 Message-ID: <4BB4A89F.7030707@maxeaves.co.uk> References: <4BB49E4D.1090809@maxeaves.co.uk> <4BB4A461.5030704@redhat.com> Reply-To: max@maxeaves.co.uk Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4BB4A461.5030704@redhat.com> Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org Cc: Doug Ledford List-Id: linux-raid.ids Doug, Thank you very much for that; a great relief off my shoulders. You are right - there is a config file located in /etc/sysconfig/raid-check. I've changed ENABLED to no. Amazing - I've learnt something today. Thanks once again. Max On 01/04/10 14:49, Doug Ledford wrote: > On 04/01/2010 09:23 AM, Max Eaves wrote: > >> Hi there, >> >> I hope this gets through....my first posting on this dist.list. >> >> I am running Centos 5.4 with a 2.6.18-164.15.1.el5 kernel (x86_64) >> kernel using a rather "homebrew" backblaze system >> (http://blog.backblaze.com/) system. >> >> The mdadm version is: mdadm - v2.6.9 - 10th March 2009 >> >> It uses a number of Silicon Image 3124 (sIL 3124) cards and a number of >> multiplier port cards (sIL3132) to read a large number of disks. >> >> I have 45 disks arranged into 3 mdadm raid sets of 15 disks. These 15 >> disks are raided using RAID6. >> >> The problem I have is this: >> >> At random times, the RAID decides that it needs to resynchronise >> /dev/md10 /dev/md11 and /dev/md12. There is no error or log event in >> /var/log/messages, but the first thing I notice is that the performance >> of the RAID array drops, and checking out "cat /proc/mdadm" shows all >> three RAID re synchronising themselves. >> >> ARRAY /dev/md0 level=raid1 num-devices=2 >> uuid=7d7b19e6:56cc90cc:3cb166bd:b8086f29 (system boot) (not a problem) >> ARRAY /dev/md1 level=raid1 num-devices=2 >> uuid=3782d93d:a491ffd4:f32c1014:94a2b3f7 (system LVM) (not a problem) >> ARRAY /dev/md10 level=raid6 num-devices=15 >> uuid=5ca86e2a-3b86-4c0b-9a7a-59143bdcd0f1 (partition 1) (problem) >> ARRAY /dev/md11 level=raid6 num-devices=15 >> uuid=61188c90-4825-44c5-8fac-9bc82a5799fe (partition 2) (problem) >> ARRAY /dev/md12 level=raid6 num-devices=15 >> uuid=fa939816-1d0f-4eaa-98dd-c131449c3921 (partition 3) (problem) >> >> These re-synchronisation events take about a week to complete (the RAID >> is 18TB a pop) >> >> I know that the performance of this system is not great, but I wonder if >> this resynchronisation is occurring because of some I/O time-out. >> >> Oddly enough, a restart of the server fixes the problem for a couple of >> days, and then problem occurs again (humm - not good). >> >> I'm happy to post logs etc....just let me know what you need. >> > Disable /etc/cron.weekly/99-raid-check. They aren't resyncronizing, > they are actually just checking themselves for consistency, but because > the 2.6.18 kernel didn't have a different word for it in the output of > /proc/mdstat it just looks that way. I can't remember if the version of > mdadm in centos 5.4 has the /etc/sysconfig/raid-check config file, but > if it does, it's easy to disable the weekly check there. > > >