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=-0.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 4785CC432C0 for ; Wed, 27 Nov 2019 15:11:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1AE4D20674 for ; Wed, 27 Nov 2019 15:11:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="DFcXYBCQ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727091AbfK0PLM (ORCPT ); Wed, 27 Nov 2019 10:11:12 -0500 Received: from mail-ot1-f50.google.com ([209.85.210.50]:37324 "EHLO mail-ot1-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726514AbfK0PLM (ORCPT ); Wed, 27 Nov 2019 10:11:12 -0500 Received: by mail-ot1-f50.google.com with SMTP id k14so3668225otn.4 for ; Wed, 27 Nov 2019 07:11:11 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:from:date:message-id:subject:to; bh=0qtodSRCiXepx7Tjoavti29284BmHUtJ6tnz5IjtUo8=; b=DFcXYBCQsEUxbMfbUfMAkLzyB5v1EZApo00E9j1PkvhHYyOlxis4Y+9U09wmHdPaFv tl6sLKiLE6WEmXv4SpPUmFvVf8B0XnzipzkbyZMR9FZVW7AdClkvqYAqTWmElIDadMgo Lv62ok3uTqI80SrrhEKeEoWMsEcs48yNtR1tC9uuUVZmLKIoiLjeG2NYrBcB4UOB87cE cNmlCYUkOv1iIwHU7IzWxr6/dATmMisPAYmpdMmS6g/VbqKTMmYBAOPGKTzi3YRMRP/2 MbrX0gExCTSCLvx2WpXFmMLbLiH7NA8tJwOhhldoR+mND9HmlM062WyQEyDKfFnk/mF1 xQqA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:from:date:message-id:subject:to; bh=0qtodSRCiXepx7Tjoavti29284BmHUtJ6tnz5IjtUo8=; b=sWvgd4e3W7phCu6l/Tal1EJ8jrSvkSMTWBcqLaxMFqpoEo3P1yxUxJwwQOmcoe6tNn Obid2gUfLNCWz+V1HmhtTiQ8O4d9w0pxLxSfPPiyKFTshi8AfdO+WapacBr//VSvoh0u 4RuD5/sdawiGaWmVdRkby65CHnk0/hXRv72LJE9WcHuJBh0DooHaFY4Brm9JpO6e1fSV pgZK47cS+28eBoOgkwRwROwWeJ6puZaG8PafNyB3D8sdXmCEW0yy8hu+qNOyF+zEkyce CcTnG+EVfC87/uxL/3vGXGKd9wpGPJvD/mEdVJwq//ARUF6bkSSybirZmDO0Qf1yb4R7 tFgw== X-Gm-Message-State: APjAAAXPrNTqMbmSgMq8LENcP3hYOBEJH9DRge1XuhBott5tma3J+ATd K3DRS5E9V5LvOn0pxpvgWRtVzL7Y7Oak2Lf/jmERYwWR088= X-Google-Smtp-Source: APXvYqydWe35kxjUGPtIXOIeRoFkRkGBAgVCU5cAjALjd8ktpyNSQpIuynv3qBagKsVjHobw4C6lTYB1T0Wrdhkk1Ko= X-Received: by 2002:a05:6830:2308:: with SMTP id u8mr3855186ote.2.1574867471022; Wed, 27 Nov 2019 07:11:11 -0800 (PST) MIME-Version: 1.0 From: Jorge Bastos Date: Wed, 27 Nov 2019 15:11:00 +0000 Message-ID: Subject: RAID5 scrub performance To: Btrfs BTRFS Content-Type: text/plain; charset="UTF-8" Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org I believe this is a known issue but wonder if there's something I can do do optimize raid5 scrub speed, or if anything is in the works to improve it. kernel 5.3.8 btrfs-progs 5.3.1 Single disk filesystem is performing as expected: UUID: 9c0ed213-d9c5-4e93-b9db-218b43533c15 Scrub started: Tue Nov 26 21:58:20 2019 Status: finished Duration: 2:24:32 Total to scrub: 1.04TiB Rate: 125.17MiB/s Error summary: no errors found 4 disk raid5 (raid1 metadata) on the same server using the same model disks as above: UUID: b75ee8b5-ae1c-4395-aa39-bebf10993057 Scrub started: Wed Nov 27 07:32:46 2019 Status: running Duration: 7:34:50 Time left: 1:52:37 ETA: Wed Nov 27 17:00:18 2019 Total to scrub: 1.20TiB Bytes scrubbed: 982.05GiB Rate: 36.85MiB/s Error summary: no errors found 6 SSD raid5 (raid1 metadata) also on the same server, still slow for SSDs but at least scrub performance is acceptable: UUID: e072aa60-33e2-4756-8496-c58cd8ba6053 Scrub started: Wed Nov 27 15:08:31 2019 Status: running Duration: 0:01:40 Time left: 1:40:11 ETA: Wed Nov 27 16:50:24 2019 Total to scrub: 3.24TiB Bytes scrubbed: 54.37GiB Rate: 556.73MiB/s Error summary: no errors found I still have some reservations about btrfs raid5/6, so use mostly for smaller filesystems for now, but this slow scrub performance will result in multi-day scrubs for a large filesystem, which isn't very practical. Thanks, Jorge