From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-btrfs-owner@vger.kernel.org>
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 AB181C61DA4
	for <linux-btrfs@archiver.kernel.org>; Sun, 19 Feb 2023 19:11:13 +0000 (UTC)
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S231223AbjBSTLM (ORCPT <rfc822;linux-btrfs@archiver.kernel.org>);
        Sun, 19 Feb 2023 14:11:12 -0500
Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35508 "EHLO
        lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S230372AbjBSTLL (ORCPT
        <rfc822;linux-btrfs@vger.kernel.org>);
        Sun, 19 Feb 2023 14:11:11 -0500
Received: from ciao.gmane.io (ciao.gmane.io [116.202.254.214])
        by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E84DFD524
        for <linux-btrfs@vger.kernel.org>; Sun, 19 Feb 2023 11:11:08 -0800 (PST)
Received: from list by ciao.gmane.io with local (Exim 4.92)
        (envelope-from <gcfb-btrfs-devel-moved1-3@m.gmane-mx.org>)
        id 1pTp5W-0007Ru-Gc
        for linux-btrfs@vger.kernel.org; Sun, 19 Feb 2023 20:11:06 +0100
X-Injected-Via-Gmane: http://gmane.org/
Mail-Followup-To: linux-btrfs@vger.kernel.org
To:     linux-btrfs@vger.kernel.org
From:   Torsten Bronger <bronger@physik.rwth-aachen.de>
Subject: Re: Why is converting from RAID1 to single in Btrfs an I/O-intensive operation?
Date:   Sun, 19 Feb 2023 20:04:28 +0100
Organization: Phoenix Foundation
Message-ID: <87k00dmq83.fsf@physik.rwth-aachen.de>
References: <87wn4fiec8.fsf@physik.rwth-aachen.de>
        <04ddea4e-4823-00dc-c32c-700d9f7e1fef@libero.it>
        <87a61bi4pj.fsf@physik.rwth-aachen.de>
        <8531c30e-885b-1d8d-314b-5167ed0874ac@libero.it>
Mime-Version: 1.0
Content-Type: text/plain; charset=iso-8859-1
Content-Transfer-Encoding: 8bit
User-Agent: Gnus/5.13 (Gnus v5.13)
Cancel-Lock: sha1:mZ7pS6+rehu5yMLrysOktMf/p0Y=
X-PGP-Fingerprint: C5C8 D6E2 79D2 EFE9 8C0F  6D77 D5E3 CEFC 9F51 6B77
X-Home-Page: http://www.wikipedia.org/wiki/User:Bronger
X-Face: +wpw"|jN2Fde|7<r"A\7[g0RGE#"N'WgB|46ohZy$RfV+Y!oH=FKMC>_<EQ_IdY;pJcjJrx
 {m$r$vTG>lKBa0\7!_6<ouwhB1|a+k#?z597ims{Y+POGr7Z{,b]wj]6Z"PqUHzA2\|m(:>suIE_m!
 x)'S9ytBu8tkt'k779jbzQ4o|p+@H_DCrIdnKG]E*w
X-Binford: 6100 (more power)
X-Accept-Language: de, en
Mail-Copies-To: never
Precedence: bulk
List-ID: <linux-btrfs.vger.kernel.org>
X-Mailing-List: linux-btrfs@vger.kernel.org

Hallöchen!

Goffredo Baroncelli writes:

> [...] 
>
> Just for curiosity, I know that the BTRFS RAID1 is not the fastest
> implementation, but how slower is in your "I/O-intensive
> operation".

What exactly do you want to compare?  Be that as it may, I have no
benchmarks.  Originally, I was just wondering why RAID1 --> single
may take hours, given that all data is on both disks anyway.

Regards,
Torsten.

-- 
Torsten Bronger