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 9B99EC43217 for ; Sun, 27 Nov 2022 18:08:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229487AbiK0SIf (ORCPT ); Sun, 27 Nov 2022 13:08:35 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33416 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229436AbiK0SIf (ORCPT ); Sun, 27 Nov 2022 13:08:35 -0500 Received: from len.romanrm.net (len.romanrm.net [91.121.86.59]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C440CB1ED for ; Sun, 27 Nov 2022 10:08:32 -0800 (PST) Received: from nvm (nvm2.home.romanrm.net [IPv6:fd39::4a:3cff:fe57:d6b5]) by len.romanrm.net (Postfix) with SMTP id 0D3A840211; Sun, 27 Nov 2022 18:08:28 +0000 (UTC) Date: Sun, 27 Nov 2022 23:08:28 +0500 From: Roman Mamedov To: Wol Cc: Reindl Harald , John Stoffel , David T-G , Linux RAID list Subject: Re: how do i fix these RAID5 arrays? Message-ID: <20221127230828.3cfe728b@nvm> In-Reply-To: References: <20221123220736.GD19721@jpo> <20221124032821.628cd042@nvm> <20221124211019.GE19721@jpo> <25474.28874.952381.412636@quad.stoffel.home> <62b72b4e-8461-e616-1227-4dcef8853143@youngman.org.uk> <7316d29a-bab6-b8a2-5c77-803af8de378b@thelounge.net> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-raid@vger.kernel.org On Sun, 27 Nov 2022 14:33:37 +0000 Wol wrote: > If raid supports trim, that means it intercepts the trim commands, and > uses it to keep track of what's being used by the layer above. > > In other words, if the filesystem is only using 10% of the disk, > supporting trim means that raid knows which 10% is being used and only > bothers syncing that! Not sure which RAID system you are speaking of, but that's not presently implemented in mdadm RAID. It does not use TRIM of the array to keep track of unused areas on the underlying devices, to skip those during rebuilds. And I am unaware of any other RAID that does. Would be nice to have though. -- With respect, Roman