From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mikael Abrahamsson Subject: Re: raid6 check/repair Date: Wed, 5 Dec 2007 07:53:45 +0100 (CET) Message-ID: References: <474431BF.30103@ph.tum.de> <18244.64972.172685.796502@notabene.brown> <4745B375.4030500@ph.tum.de> <18254.21949.441607.134763@notabene.brown> <474F4880.8080300@eyal.emu.id.au> <47502140.1080601@ph.tum.de> <1196650421.14411.10.camel@elara.tcw.local> <47546019.5030300@ph.tum.de> <18261.49547.588360.436369@base.ty.sabi.co.UK> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Return-path: In-Reply-To: <18261.49547.588360.436369@base.ty.sabi.co.UK> Sender: linux-raid-owner@vger.kernel.org To: Linux RAID List-Id: linux-raid.ids On Tue, 4 Dec 2007, Peter Grandi wrote: > ms> and linux-raid / mdadm did not complain or do anything. > > The mystic version of Linux-RAID is in psi-test right now :-). > > To me RAID does not seem the right abstraction level to deal with > this problem; and perhaps the file system level is not either, > even if ZFS tries to address some of the problem. Hm. If I run a "check" on a raid1, I would expect it to read data from both disks and compare them, and complain if it's not identical. Are you sure you really mean what you're saying here? I do realise that if the corruption happens above the raid layer then there is nothing we can do, but if md asks to write a block to two raid1 disks and the system corrupts the write and writes different data to the two different drives in the raid1, then when md does check at a later time and discovers this, it should scream bloody murder, choose one of the data and replicate it to the other one...? I know this might as well be the wrong data, but md can't figure that out, but it should correct the *raid1* inconsistancy, which I think is what the person you replied to meant? -- Mikael Abrahamsson email: swmike@swm.pp.se