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 3407FC00140 for ; Fri, 12 Aug 2022 07:24:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236539AbiHLHYG (ORCPT ); Fri, 12 Aug 2022 03:24:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55992 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235029AbiHLHYF (ORCPT ); Fri, 12 Aug 2022 03:24:05 -0400 Received: from smtp.hosts.co.uk (smtp.hosts.co.uk [85.233.160.19]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4B639A50E7 for ; Fri, 12 Aug 2022 00:24:03 -0700 (PDT) Received: from host86-128-157-135.range86-128.btcentralplus.com ([86.128.157.135] helo=[192.168.1.218]) by smtp.hosts.co.uk with esmtpa (Exim) (envelope-from ) id 1oMP1U-00060W-7j; Fri, 12 Aug 2022 08:24:00 +0100 Message-ID: Date: Fri, 12 Aug 2022 08:23:59 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.12.0 Subject: Re: mirroring existing boot drive sanity check Content-Language: en-GB To: Pascal Hambourg , David T-G , linux-raid@vger.kernel.org References: <8319a7ea67dc601c8ca4556ff15702d5@justpickone.org> <014ce113-3c6d-ea1d-a576-cb06e5126748@plouf.fr.eu.org> From: Wols Lists In-Reply-To: <014ce113-3c6d-ea1d-a576-cb06e5126748@plouf.fr.eu.org> 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 On 11/08/2022 22:26, Pascal Hambourg wrote: > However I do not think it is possible to cleanly boot from an > unpartitioned drive used as a software RAID member, as a RAID capable > boot loader could hardly fit in the 4-KiB area before the RAID > superblock. So you still have to create a partition table on the raw > drives. Also, if you use GPT format and GRUB boot loader, you need to > create a small (100 kB to 1 MB) partition with type "BIOS boot" (or > libparted bios_grub flag). Firstly, is there a 4K block there? iirc it's only 1.2 that leaves said block. And secondly, does raid assume that 4K space belongs to it? I know it's seen as a safety space, so there's nothing permanent left there, but that's no guarantee raid doesn't think "that's mine, I'll stash something there temporarily". After all, the space allocated explicitly begins at the start of the 4K. (That's completely different to the rouge tools the space is there to protect - those tools that think "that's nobody's, I'll just grab it".) Cheers, Wol