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 X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 08417C433ED for ; Sat, 8 May 2021 14:10:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C392D610A0 for ; Sat, 8 May 2021 14:10:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229528AbhEHOL6 (ORCPT ); Sat, 8 May 2021 10:11:58 -0400 Received: from open-std.org ([93.90.116.65]:33070 "EHLO www.open-std.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229500AbhEHOL5 (ORCPT ); Sat, 8 May 2021 10:11:57 -0400 X-Greylist: delayed 1407 seconds by postgrey-1.27 at vger.kernel.org; Sat, 08 May 2021 10:11:56 EDT Received: by www.open-std.org (Postfix, from userid 500) id 9F11A356EC5; Sat, 8 May 2021 15:47:26 +0200 (CEST) Date: Sat, 8 May 2021 15:47:26 +0200 From: keld@keldix.com To: d tbsky Cc: Reindl Harald , list Linux RAID Subject: Re: raid10 redundancy Message-ID: <20210508134726.GA11665@www5.open-std.org> References: <8626adeb-696c-7778-2d5e-0718ed6aefdb@redhat.com> <6db10ef4-e087-3940-4870-e5d9717b853f@thelounge.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.2.2i Precedence: bulk List-ID: X-Mailing-List: linux-raid@vger.kernel.org On Fri, May 07, 2021 at 09:28:35AM +0800, d tbsky wrote: > Reindl Harald > > Am 06.05.21 um 11:57 schrieb d tbsky: > > > if losing two disks will madam find out the raid can be rebuilded safely or not? > > > > it's pretty simple > > > > * if you lose the wrong disks all is gone > > * if you lsoe the right disks no problem > > that's seems reasonable. I will give it a try. My understanding is that raid10 - all layouts - are really raid0 and then raid 1 on top. If you loose two disks you loose the whole raid in 2 out of 3 cases in a 4 disk setup. If it was raid0 over a raid1 you would only lose the whole raid in one out of 3. raid1 raid0 raid0 d1 d2 d3 d4 gone d1+d2 survives d3+d4 gone d1+d3 dead gone d1+d4 dead should be. raid0 raid1 raid1 d1 d2 d3 d4 gone d1+d2 dead gone d1+d3 survives gone d1+d4 survives keld