From mboxrd@z Thu Jan 1 00:00:00 1970 From: Brad Campbell Subject: Partiy error detection - was Re: ext3 journal on software raid (was Re: PROBLEM: Kernel 2.6.10 crashing repeatedly and hard) Date: Mon, 03 Jan 2005 14:18:21 +0400 Message-ID: <41D91BED.5020302@wasp.net.au> References: <41D45C1F.5030307@tls.msk.ru> <20050102194240.GE99565@caffreys.strugglers.net> <5h1ma2-asq.ln1@news.it.uc3m.es> <20050103003005.GG99565@caffreys.strugglers.net> <2rana2-0if.ln1@news.it.uc3m.es> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <2rana2-0if.ln1@news.it.uc3m.es> Sender: linux-raid-owner@vger.kernel.org To: "Peter T. Breuer" Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids Peter T. Breuer wrote: > And there is a risk of silent corruption on all raid systems - that is > well known. DIfferent raid systems do different thigs to compensate, > such as periodically recalculating the parity on everything. But when > you have redundant data and a corruption occurs, which of the two > datasets do you believe? You have to choose one of them! You guess > wrong half the time, if you guess ("you" is a raid system). Hence > "silent corruption". Just on this point. With RAID-6 I guess you can get a majority rules type of ruling on which data block is the dud. Unless you come up with 3 different results in which case something is really not right in lego land. I wonder perhaps about a userspace app that you can run to check all the parity blocks. On RAID-5 it should be able to tell you, you have a naff stripe, but on RAID-6 in theory if it's only a single drive that is a problem you should be able to correct the block. Regards, Brad