From mboxrd@z Thu Jan 1 00:00:00 1970 From: Phil Turmel Subject: Re: question about the best suited RAID level/layout Date: Fri, 05 Jul 2013 22:19:59 -0400 Message-ID: <51D77ECF.5090909@turmel.org> 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> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1373073066.10569.30.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 07/05/2013 09:11 PM, Christoph Anton Mitterer wrote: > On Fri, 2013-07-05 at 09:36 -0400, Phil Turmel wrote: >> You picked "redundancy". Leaves only only one axis to consider: speed >> vs. capacity. > Well thinking about that "raid6check" tool you told me over in the other > thread,... > which AFAIU does what I was talking about, namely telling me which block > is the correct one if I have bad blocks (and the disk itself can't tell) > and not whole drive failures,.. where at least a two-block copy RAID10 > would not be able to... > ...then I think RAID6 is THE solution for me, given resilience has the > highest priority, as RAID10 with c/f/o=3 cannot do that. I think you should read Neil's blog entry before you get too excited about raid6check. You can only trust its decisions when you are confident that the problems it finds are *only* due to silent read errors. MD raid does not carry the per-block metadata needed to distinguish silent read errors from incomplete writes or out-of-band writes to member disks. Hopefully, btrfs will fill this void (eventually). http://neil.brown.name/blog/20100211050355 Phil