From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp-16-i6.italiaonline.it ([213.209.14.16]:55220 "EHLO libero.it" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751133AbeECTQU (ORCPT ); Thu, 3 May 2018 15:16:20 -0400 Reply-To: kreijack@inwind.it Subject: Re: [PATCH 00/14 RFC] Btrfs: Add journal for raid5/6 writes To: Chris Mason , "Austin S. Hemmelgarn" , Roman Mamedov , Liu Bo Cc: linux-btrfs@vger.kernel.org References: <20170801161439.13426-1-bo.li.liu@oracle.com> <20170801222547.35d1bd03@natsu> <50312ea2-a0bf-09f7-8bc0-804c3a087ae4@gmail.com> <5800c104-5b03-8d48-bb49-b1710be05cd0@fb.com> From: Goffredo Baroncelli Message-ID: <0f1198b1-bad0-f9d3-dda8-79a67b329e16@libero.it> Date: Thu, 3 May 2018 21:16:14 +0200 MIME-Version: 1.0 In-Reply-To: <5800c104-5b03-8d48-bb49-b1710be05cd0@fb.com> Content-Type: text/plain; charset=utf-8 Sender: linux-btrfs-owner@vger.kernel.org List-ID: On 08/02/2017 08:47 PM, Chris Mason wrote: >> I agree, MD pretty much needs a separate device simply because they can't allocate arbitrary space on the other array members.  BTRFS can do that though, and I would actually think that that would be _easier_ to implement than having a separate device. >> >> That said, I do think that it would need to be a separate chunk type, because things could get really complicated if the metadata is itself using a parity raid profile. > > Thanks for running with this Liu, I'm reading through all the patches. I do agree that it's better to put the logging into a dedicated chunk type, that way we can have it default to either double or triple mirroring. Sorry for reply a bit late :-), however it should be sufficient to start the writes from the stripe boundary. For a filesystem this is complicate to grant, however for a journal it would be more simple to do; BR G.Baroncelli -- gpg @keyserver.linux.it: Goffredo Baroncelli Key fingerprint BBF5 1610 0B64 DAC6 5F7D 17B2 0EDA 9B37 8B82 E0B5