From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from srv2.trombetti.net ([65.254.53.252]:4038 "EHLO server" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752631AbaAFME6 (ORCPT ); Mon, 6 Jan 2014 07:04:58 -0500 Message-ID: <52CA9A97.4000803@shiftmail.org> Date: Mon, 06 Jan 2014 12:59:19 +0100 From: joystick MIME-Version: 1.0 To: Andrea Mazzoleni CC: linux-raid@vger.kernel.org, linux-btrfs@vger.kernel.org Subject: Re: [RFC v2 0/2] New RAID library supporting up to six parities References: <1389000716-3274-1-git-send-email-amadvance@gmail.com> In-Reply-To: <1389000716-3274-1-git-send-email-amadvance@gmail.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Sender: linux-btrfs-owner@vger.kernel.org List-ID: On 06/01/2014 10:31, Andrea Mazzoleni wrote: > Hi, > > This is a port to the Linux kernel of a RAID engine that I'm currently using > in a hobby project called SnapRAID. This engine supports up to six parities > levels and at the same time maintains compatibility with the existing Linux > RAID6 one. > This is just great Andrea, thank you for such Epiphany present. Just by looking at the Subjects, it seems patch number 0/1 is missing. It might have not gotten through to the lists, or be a numbering mistake. Does your code also support (shortcut) RMW as opposed to RCW, for all parities? RMW is: for a 4k write: read just nparities+1data disks, recompute parities, write nparities+1data disks, RCW is: "read all disks" prior to recompute parities... Part of such RMW code should be in handle_stripe_dirtying which is not in your patch 0/2 but that might have been in patch 0/1 which apparently didn't get through. See this patch by Kumar for support of RMW in raid6 (raid5 has it) which unfortunately apparently wasn't merged up to now: http://marc.info/?l=linux-raid&m=136624783417452&w=2 Thank you J.