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 AD034C4332F for ; Sun, 27 Nov 2022 22:08:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229619AbiK0WIe (ORCPT ); Sun, 27 Nov 2022 17:08:34 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46070 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229555AbiK0WId (ORCPT ); Sun, 27 Nov 2022 17:08:33 -0500 Received: from mail.thelounge.net (mail.thelounge.net [91.118.73.15]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3083E1BD for ; Sun, 27 Nov 2022 14:08:31 -0800 (PST) Received: from [10.10.10.2] (rh.vpn.thelounge.net [10.10.10.2]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-256) server-digest SHA256) (No client certificate requested) (Authenticated sender: h.reindl@thelounge.net) by mail.thelounge.net (THELOUNGE MTA) with ESMTPSA id 4NL2mY1PM3zXLf; Sun, 27 Nov 2022 23:08:24 +0100 (CET) Message-ID: <5ae1729b-d084-384c-04ff-165b9e3298f9@thelounge.net> Date: Sun, 27 Nov 2022 23:08:23 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.5.0 Subject: Re: how do i fix these RAID5 arrays? Content-Language: en-US To: Wol , piergiorgio.sartor@nexgo.de, John Stoffel Cc: David T-G , Linux RAID list References: <20221123220736.GD19721@jpo> <20221124032821.628cd042@nvm> <20221124211019.GE19721@jpo> <25474.28874.952381.412636@quad.stoffel.home> <0c7ad6eff626c8440734909300ebc50d9b1bf615@nexgo.de> <4379b4f4-9e7f-a7dc-fc29-6c22b12bf3ea@thelounge.net> <531e8606-94b4-d48b-1d5a-72cc7d078755@youngman.org.uk> From: Reindl Harald Organization: the lounge interactive design In-Reply-To: <531e8606-94b4-d48b-1d5a-72cc7d078755@youngman.org.uk> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-raid@vger.kernel.org Am 27.11.22 um 23:05 schrieb Wol: > On 27/11/2022 18:21, Reindl Harald wrote: >>> If the array is 99% full, MD or ZFS/BTRFS have >>> same behaviour, in terms of reliability. >>> If the array is 0% full, as well >> >> you completly miss the point! >> >> if your mdadm-array is built with 6 TB drivres wehn you replace a >> drive you need to sync 6 TB no matter if 10 MB or 5 TB are actually used > > And you are also completely missing the point! > > When mdadm creates an array - IF IT SUPPORTED TRIM - you could tell it > "this is a blank array, don't bother initialising it". So it would > initialise an internal bitmap to say "all these stripes are empty" you could - but it don't > tldr - there is no reason why mdadm couldn't implement trim, and if it > did, then it would know how much of the array needed to be sync'd and > how much didn't need bothering with who the hell cares about what it *could*? it simply don't and that's state of play that's the difference between a filesystem on top of mdadm versus a filesystem which implements RAID on it's own that's the whole point: what things actually do