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=-2.2 required=3.0 tests=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 45E62C55185 for ; Wed, 22 Apr 2020 10:55:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2948120775 for ; Wed, 22 Apr 2020 10:55:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729100AbgDVKzM (ORCPT ); Wed, 22 Apr 2020 06:55:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40476 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728507AbgDVKzL (ORCPT ); Wed, 22 Apr 2020 06:55:11 -0400 Received: from wp558.webpack.hosteurope.de (wp558.webpack.hosteurope.de [IPv6:2a01:488:42:1000:50ed:8250::]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 230ACC03C1A8 for ; Wed, 22 Apr 2020 03:55:11 -0700 (PDT) Received: from mail1.i-concept.de ([130.180.70.237] helo=[192.168.122.235]); authenticated by wp558.webpack.hosteurope.de running ExIM with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) id 1jRD25-0002jJ-L2; Wed, 22 Apr 2020 12:55:09 +0200 Subject: Re: RAID 1 | Newbie Question To: Hugo Mills , linux-btrfs@vger.kernel.org References: <20200422104403.GE32577@savella.carfax.org.uk> From: Stefanie Leisestreichler Message-ID: Date: Wed, 22 Apr 2020 12:55:08 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <20200422104403.GE32577@savella.carfax.org.uk> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: de-DE Content-Transfer-Encoding: 7bit X-bounce-key: webpack.hosteurope.de;stefanie.leisestreichler@peter-speer.de;1587552911;cffa8089; X-HE-SMSGID: 1jRD25-0002jJ-L2 Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On 22.04.20 12:44, Hugo Mills wrote: > You can't set up btrfs RAID-1 to use only one device. It's only > possible to end up like that if you set up a 2-device RAID-1 and then > unplug a device and mount it in degraded mode. It was this sentence in the btrfs wiki, what confused me, also comments in the net that btrfs is not giving you RAID with redundant data (https://btrfs.wiki.kernel.org/index.php/FAQ): "It is possible with all of the descriptions below, to construct a RAID-1 array from two or more devices, and have those devices live on the same physical drive. This configuration does not offer any form of redundancy for your data."