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,NICE_REPLY_A,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 B7A3DC433E2 for ; Mon, 14 Sep 2020 17:27:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 52F6320771 for ; Mon, 14 Sep 2020 17:27:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726068AbgINR1M (ORCPT ); Mon, 14 Sep 2020 13:27:12 -0400 Received: from smtp.hosts.co.uk ([85.233.160.19]:49261 "EHLO smtp.hosts.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726341AbgINR0j (ORCPT ); Mon, 14 Sep 2020 13:26:39 -0400 Received: from host86-136-163-47.range86-136.btcentralplus.com ([86.136.163.47] helo=[192.168.1.64]) by smtp.hosts.co.uk with esmtpa (Exim) (envelope-from ) id 1kHsFN-0001ql-AS; Mon, 14 Sep 2020 18:26:33 +0100 Subject: Re: Linux raid-like idea To: Phillip Susi References: <1cf0d18c-2f63-6bca-9884-9544b0e7c54e.ref@aim.com> <1cf0d18c-2f63-6bca-9884-9544b0e7c54e@aim.com> <5F54146F.40808@youngman.org.uk> <274cb804-9cf1-f56c-9ee4-56463f052c09@aim.com> <38f9595b-963e-b1f5-3c29-ad8981e677a7@aim.com> <9220ea81-3a81-bb98-22e3-be1a123113a1@youngman.org.uk> <87k0ww6ztv.fsf@vps.thesusis.net> Cc: Brian Allen Vanderburg II , linux-raid@vger.kernel.org From: Wols Lists Message-ID: <5F5FA7C8.6010001@youngman.org.uk> Date: Mon, 14 Sep 2020 18:26:32 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.7.0 MIME-Version: 1.0 In-Reply-To: <87k0ww6ztv.fsf@vps.thesusis.net> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-raid-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-raid@vger.kernel.org On 14/09/20 18:19, Phillip Susi wrote: > > antlists writes: > >> Yup. Raid 6 has two parity disks, and that's mirrored to give four >> parity disks. So as an *absolute* *minimum*, raid-61 could lose four >> disks with no data loss. > > Don't you mean 5 disks? > > At best 4 lost disks paired off in each raid1 means the raid6 sees two > failures. One more disk failing isn't enough to take out another mirror > so the raid6 keeps ticking. > Well caught !!! Cheers, Wol