From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 318CDC433F5 for ; Fri, 28 Jan 2022 18:54:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239705AbiA1SyT (ORCPT ); Fri, 28 Jan 2022 13:54:19 -0500 Received: from rin.romanrm.net ([51.158.148.128]:43748 "EHLO rin.romanrm.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230165AbiA1SyS (ORCPT ); Fri, 28 Jan 2022 13:54:18 -0500 X-Greylist: delayed 586 seconds by postgrey-1.27 at vger.kernel.org; Fri, 28 Jan 2022 13:54:18 EST Received: from nvm (nvm2.home.romanrm.net [IPv6:fd39::4a:3cff:fe57:d6b5]) by rin.romanrm.net (Postfix) with SMTP id 15D7466A; Fri, 28 Jan 2022 18:44:30 +0000 (UTC) Date: Fri, 28 Jan 2022 23:44:30 +0500 From: Roman Mamedov To: Remi Gauvin Cc: Kai Krakow , linux-btrfs Subject: Re: fstab autodegrag with 5.10 & 5.15 kernels, Debian? Message-ID: <20220128234430.63f67d20@nvm> In-Reply-To: <19bf3e06-3156-99b4-4656-6ac794ad1ca8@georgianit.com> References: <10e51417-2203-f0a4-2021-86c8511cc367@gmx.com> <5e8303e3-64bf-f19a-6d42-e18ae62fd721@georgianit.com> <19bf3e06-3156-99b4-4656-6ac794ad1ca8@georgianit.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Fri, 28 Jan 2022 13:29:22 -0500 Remi Gauvin wrote: > MDraid, and any hardware raid I'm aware of, will resynchronize the 2 > copies whenever there is an unclean shutdown. which copy becomes the > new master is arbitrary, but both will be the same. I believe mdraid writes event count to each device, and the device with the highest event count (which has seen completed writes as late in time prior to shutdown as possible) will be used as the source for synchronizing the other ones. Secondly, it has a write intent bitmap, to only resync the areas that are different on that chosen device compared to the others. -- With respect, Roman