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 86D95C433F5 for ; Mon, 29 Nov 2021 21:50:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231286AbhK2Vx3 (ORCPT ); Mon, 29 Nov 2021 16:53:29 -0500 Received: from li1843-175.members.linode.com ([172.104.24.175]:45378 "EHLO mail.stoffel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231650AbhK2Vv2 (ORCPT ); Mon, 29 Nov 2021 16:51:28 -0500 Received: from quad.stoffel.org (068-116-170-226.res.spectrum.com [68.116.170.226]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by mail.stoffel.org (Postfix) with ESMTPSA id 8A30E24258; Mon, 29 Nov 2021 16:48:09 -0500 (EST) Received: by quad.stoffel.org (Postfix, from userid 1000) id 26063A7672; Mon, 29 Nov 2021 16:48:05 -0500 (EST) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <24997.19093.110727.118664@quad.stoffel.home> Date: Mon, 29 Nov 2021 16:48:05 -0500 From: "John Stoffel" To: Wol Cc: John Stoffel , linux-raid Subject: Re: Nothing wrong, but is my website advice wonky? In-Reply-To: References: <1c63e476-b253-cb17-3299-f9d09453ee19@youngman.org.uk> <12dd9f53-aab2-c487-9663-b799c2d0e8dd@youngman.org.uk> <24995.58211.78152.138025@quad.stoffel.home> X-Mailer: VM 8.2.0b under 26.1 (x86_64-pc-linux-gnu) Precedence: bulk List-ID: X-Mailing-List: linux-raid@vger.kernel.org >>>>> "Wol" == Wol writes: Wol> On 28/11/2021 20:15, John Stoffel wrote: >>>>>>> "Wol" == Wol writes: >> Wol> Problem solved! My usual problem of missing the detail... >> >> How was the problem solved? Can you provide details on the before and >> after setup? It should be trivial to test with loop back devices. >> Wol> I'd described starting with a 2-drive mirror and converting it to Wol> a 3-drive raid-5. I was actually starting with a 2-active-1-spare Wol> mirror ... Wol> So I converted it to raid-5, and because there were only two active Wol> drives, it carried on running as a degraded two-drive raid-5. Wol> Once I brought the spare into service with --raid-devices=3, it started Wol> reshaping. Ah... that explains it. Wol> The website said to add the new drive and set raid-devices to three, I Wol> misread my own stuff and thought simply converting to raid-5 would bring Wol> in the spare. >> So if you had removed the spare before hand, would it have jumped >> straight to a three drive RAID 5 setup? Wol> No - because I didn't tell it to use all three drives. >> And curious why you didn't >> goto RAID6? RAID5 just makes me nervous these days, I don't trust it >> since drives tend to fail in waves. Wol> Well, with two DVD drives and a floppy in an old chassis, I've Wol> only got room for three drives. Well, there should be room for Wol> four, but my drives are a bit too fat ... :-) I understand. We all have to work within our limits. Wol> Plus (1) I've had no trouble so far with my drives (famous last words), Wol> (2) the drives are two new Ironwolves and an old Barracuda so I'm only Wol> likely to lose one so long as I keep an eye on things, and (3) all the Wol> drives have dm-integrity on them, so a corrupt drive should sort itself out. >> But in my home system, I also mostly just mirror (or even triple >> mirror!) my important data for both speed and ease of recovery. >> Wol> The trouble with a plain mirror is if your data is corrupted ... Wol> And if you've got raid you need to keep an eye on it. I'm planning to Wol> get an 8TB drive for backups ... probably configure it to snapshot once Wol> a week (I'm running lvm over raid over dm-integrity) and then use rsync Wol> to back up the volume over the network. Mind you I'm going to have to Wol> learn a lot of rsync - configure client/server and then get it to back Wol> up just the one file ... I've got an external USB-3 4tb drive I'm running rclone to, and planning on taking it to the bank one of these days when I remember to do so.