From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bas van Schaik Subject: Re: Doing 'echo repair > /sys/devices/virtual/block/md?/md/sync_action' does not result in mismatch_cnt of 0 on RAID-6? Date: Tue, 15 Mar 2011 13:43:01 +0000 Message-ID: <4D7F6CE5.4010303@tuxes.nl> References: <4D7F4DF3.7010804@tuxes.nl> <20110315121351.GA7190@cthulhu.home.robinhill.me.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20110315121351.GA7190@cthulhu.home.robinhill.me.uk> Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids On 15/03/11 12:13, Robin Hill wrote: > On Tue Mar 15, 2011 at 11:30:59AM +0000, Bas van Schaik wrote: >> All, >> >> I'm seeing a non-zero mismatch_cnt (in fact, it's 1704) on my RAID-6 >> array consisting of 8 devices on kernel 2.6.38. After replacing some >> hardware, I decided to trigger a MD repair by issuing: >> echo repair > /sys/devices/virtual/block/md5/md/sync_action >> >> Directly after issuing this command, the mismatch_cnt is reset to 0 and >> MD starts checking the array. However, the mismatch_cnt increases during >> this check - resulting in exactly the same count as seen before. >> Shouldn't 'repair' yield a zero mismatch_cnt? I think I have seen >> 'repair' work on other RAID-6 arrays? >> > The mismatch_cnt is incremented during repair to indicate how many > errors were repaired. If you want to be certain though, you'd need to > re-run 'check' afterwards. Sorry about that - I was sure the mismatch_cnt was reset after a repair on a different machine, but apparently I was wrong. The 'check' is running right now, I hope you are right! If not, of course I'll let you know. My other question is still standing: > Furthermore, theoretically it should be possible to indicate which > device in the RAID-6 array contains the inconsistent data, or am I > mistaking? If so, that would certainly be a nice feature to see > implemented, as it would help diagnosing problems. Am I indeed correct in thinking this? Thanks, Bas