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 558E5C4332F for ; Fri, 25 Nov 2022 13:30:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229683AbiKYNa4 (ORCPT ); Fri, 25 Nov 2022 08:30:56 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57328 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229531AbiKYNa4 (ORCPT ); Fri, 25 Nov 2022 08:30:56 -0500 Received: from www18.qth.com (www18.qth.com [69.16.238.59]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 95B7223EBB for ; Fri, 25 Nov 2022 05:30:55 -0800 (PST) Received: from [73.207.192.158] (port=50696 helo=jpo) by www18.qth.com with esmtpsa (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1oyYnD-0004fI-4e for linux-raid@vger.kernel.org; Fri, 25 Nov 2022 07:30:54 -0600 Date: Fri, 25 Nov 2022 13:30:53 +0000 From: David T-G To: Linux RAID list Subject: about linear and about RAID10 (was "Re: how do i fix these RAID5 arrays?") Message-ID: <20221125133050.GH19721@jpo> References: <20221123220736.GD19721@jpo> <20221124032821.628cd042@nvm> <20221124211019.GE19721@jpo> <512a4cdd-9013-e158-7c77-7409cd0dc3a1@youngman.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <512a4cdd-9013-e158-7c77-7409cd0dc3a1@youngman.org.uk> User-Agent: Mutt/1.10.1 (2018-07-13) X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - www18.qth.com X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - justpickone.org X-Get-Message-Sender-Via: www18.qth.com: authenticated_id: dmail@justpickone.org X-Authenticated-Sender: www18.qth.com: dmail@justpickone.org X-Source: X-Source-Args: X-Source-Dir: Precedence: bulk List-ID: X-Mailing-List: linux-raid@vger.kernel.org Wol, et al -- ...and then Wol said... % On 24/11/2022 21:10, David T-G wrote: % > How is linear different from RAID0? I took a quick look but don't quite % > know what I'm reading. If that's better then, hey, I'd try it (or at % > least learn more). % % Linear tacks one drive on to the end of another. Raid-0 stripes across all % drives. Both effectively combine a bunch of drives into one big drive. Ahhhhh... I gotcha. Thanks. % ... % % That's why there's raid-10. Note that outside of Linux (and often inside) % when people say "raid-10" they actually mean "raid 1+0". That's two striped % raid-0's, mirrored. That's basically what I have on the web server: jpo:~ # mdadm -D /dev/md41 | egrep '/dev|Level' /dev/md41: Raid Level : raid1 0 8 17 0 active sync /dev/sdb1 1 8 34 1 active sync /dev/sdc2 jpo:~ # mdadm -D /dev/md42 | egrep '/dev|Level' /dev/md42: Raid Level : raid1 0 8 18 0 active sync /dev/sdb2 1 8 33 1 active sync /dev/sdc1 jpo:~ # mdadm -D /dev/md40 | egrep '/dev|Level' /dev/md40: Raid Level : raid0 0 9 41 0 active sync /dev/md/md41 1 9 42 1 active sync /dev/md/md42 jpo:~ # jpo:~ # jpo:~ # parted /dev/sdb p Model: ATA ST4000VN008-2DR1 (scsi) Disk /dev/sdb: 4001GB Sector size (logical/physical): 512B/4096B Partition Table: gpt Disk Flags: Number Start End Size File system Name Flags 1 1049kB 2000GB 2000GB Raid1-1 2 2000GB 4001GB 2000GB Raid1-2 4 4001GB 4001GB 860kB ext2 Seag4000-ZDHB2X37-ext2 jpo:~ # parted /dev/sdc p Model: ATA ST4000VN008-2DR1 (scsi) Disk /dev/sdc: 4001GB Sector size (logical/physical): 512B/4096B Partition Table: gpt Disk Flags: Number Start End Size File system Name Flags 1 1049kB 2000GB 2000GB Raid1-2 2 2000GB 4001GB 2000GB Raid1-1 4 4001GB 4001GB 860kB Seag4000-ZDHBKZTG-ext2 % ... % % Either version (10, or 1+0), gives you get the speed of striping, and the % safety of a mirror. 10, however, can use an odd number of disks, and disks % of random sizes. That's still magic to me :-) Mirroring (but not doubling up the redundancy) on an odd number of disks?!? % % Cheers, % Wol HAND :-D -- David T-G See http://justpickone.org/davidtg/email/ See http://justpickone.org/davidtg/tofu.txt