From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bernd Schubert Subject: Re: question about the best suited RAID level/layout Date: Sun, 07 Jul 2013 14:46:21 +0200 Message-ID: <51D9631D.403@fastmail.fm> References: <1372961877.8716.43.camel@heisenberg.scientia.net> <51D5EC8A.40509@turmel.org> <1372978687.5249.52.camel@fermat.scientia.net> <51D6CBF9.2020100@turmel.org> <1373073066.10569.30.camel@fermat.scientia.net> <51D77ECF.5090909@turmel.org> <1373133349.8557.5.camel@fermat.scientia.net> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1373133349.8557.5.camel@fermat.scientia.net> Sender: linux-raid-owner@vger.kernel.org To: Christoph Anton Mitterer Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids On 07/06/2013 07:55 PM, Christoph Anton Mitterer wrote: > On Fri, 2013-07-05 at 22:19 -0400, Phil Turmel wrote: >> I think you should read Neil's blog entry > I did ;) > >> before you get too excited >> about raid6check. > Sure it's not a magic wand for all situations... and raid6check itself > seems to be rather at a early starting point... > >> You can only trust its decisions when you are >> confident that the problems it finds are *only* due to silent read >> errors. > Sure.... but at least it can be misused as kinda poor-man's integrity > check. > > AFAIU it's not yet working, that it can tell you back through the fs, > which file is affected? The block layer has no knowledge which file a block belongs to. Even for file systems that is hard task to figure out, as only inodes store information which blocks they use. So if you would want to figure out the corresponding file, you first need to scan through all inodes and search for the specific block. Once you have the corresponding inode you need to find directory-entries referencing it. So lots of expensive reverse searching. Cheers, Bernd