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=-4.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 11720C433E0 for ; Sat, 1 Aug 2020 09:05:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EBC53206D7 for ; Sat, 1 Aug 2020 09:05:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728496AbgHAJFy (ORCPT ); Sat, 1 Aug 2020 05:05:54 -0400 Received: from rin.romanrm.net ([51.158.148.128]:55214 "EHLO rin.romanrm.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725997AbgHAJFy (ORCPT ); Sat, 1 Aug 2020 05:05:54 -0400 Received: from natsu (unknown [IPv6:fd39::e99e:8f1b:cfc9:ccb8]) by rin.romanrm.net (Postfix) with SMTP id 57FBD40F; Sat, 1 Aug 2020 09:05:52 +0000 (UTC) Date: Sat, 1 Aug 2020 14:05:51 +0500 From: Roman Mamedov To: Chris Murphy Cc: Eric Wong , Btrfs BTRFS Subject: Re: raid1 with several old drives and a big new one Message-ID: <20200801140551.76348735@natsu> In-Reply-To: References: <20200731001652.GA28434@dcvr> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Thu, 30 Jul 2020 20:57:38 -0600 Chris Murphy wrote: > On Thu, Jul 30, 2020 at 6:16 PM Eric Wong wrote: > > > > Say I have three ancient 2TB HDDs and one new 6TB HDD, is there > > a way I can ensure one raid1 copy of the data stays on the new > > 6TB HDD? > > Yes. Use mdadm --level=linear --raid-devices=2 to concatenate the two > 2TB drives. Or go with a RAID0 for this, to get a nice performance benefit as well. It is a bad idea in any case to hope for any data recoverability from a half-failed linear "array". -- With respect, Roman