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=-3.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,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 AA573C433E1 for ; Sat, 22 Aug 2020 18:51:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7614320714 for ; Sat, 22 Aug 2020 18:51:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=colorremedies-com.20150623.gappssmtp.com header.i=@colorremedies-com.20150623.gappssmtp.com header.b="OMKNzwZ1" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728329AbgHVSvf (ORCPT ); Sat, 22 Aug 2020 14:51:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53024 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727856AbgHVSve (ORCPT ); Sat, 22 Aug 2020 14:51:34 -0400 Received: from mail-wr1-x435.google.com (mail-wr1-x435.google.com [IPv6:2a00:1450:4864:20::435]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 22F3FC061573 for ; Sat, 22 Aug 2020 11:51:34 -0700 (PDT) Received: by mail-wr1-x435.google.com with SMTP id z18so4852384wrm.12 for ; Sat, 22 Aug 2020 11:51:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=colorremedies-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=SC0SypEUcxsLxkFtndQhHjNjwmhauWaHSMv7bSyTACg=; b=OMKNzwZ1YdR58/NPLV88OFNLYzH9zsqddVlF7Rp395+j8YyB6vj8MS7dfR3iS+ZvGL PcHkzU+789FKTJxsIbqeJW+SHVIipkawvfkyOmREDvURWCs/g850//swWmy36jkH6Saf nh3+7J/3DRmTOddZZoIQtNGJf9qVPE39Uyq1SpDwzMQ477V/7HIrrihsYGccJD4mm+BB yLvjwVKdVtSfAUK/e1Lo2slSZEJBimdNjCb4vNQbP3aH9DJrqkJmogHLj1jexPGsGyyM kV4l5PtcehRkHDA1ys2CETBES43kQT/7yNzSX4QthZCpiOmXX5jxYc4YVVQ3mIITXfQv ArRA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=SC0SypEUcxsLxkFtndQhHjNjwmhauWaHSMv7bSyTACg=; b=OfbOSeUtZXqYct+MgqXBlDLCKqUNFth8g2ibGPa5U2DUk8rohWqbQau6ofRflDJfcP SppR1KUWxMvx4XWUI+0am5V/0qliHES2bMsZ4Qf+NUHGeLv8vemrVeFtKIgLOtd+HA1s jjEc3C+88RABpamQYmB4BwIpngOQb7uVnDobasOckSM4kJhvE1amVL+Ed+0dXFyXQIf0 FIzP7DzuW94CVoMylawECt6l4QCIsZ83diaqxKptxRf8gPb2H5RYSBfBd86FhAX28dys o/+Mq3Z/djQvcqjzOBaOYA2mwFwfF7Bshk6Iw+z1G9OSjsWyPUcVf7SEdbvVNs4aNhGS jecA== X-Gm-Message-State: AOAM533P/jd3awMaS7UcyFznCl+QRGJpX5o/vbvRim/rcP6Bt4fmCeln KjMF7Oo9DB2PtNGmCTF2ORjiulaJ2vGqMrAQXnAtnoGg5btv4n2P X-Google-Smtp-Source: ABdhPJzSk8qCZ4d3rQLEMcNEBJKuYsD6trRG2/cu9fSHE7qCiurk9ArxoQP++mOQOhLk9UI1+/9KzItMtpMwwE1ZAWw= X-Received: by 2002:adf:aace:: with SMTP id i14mr7848954wrc.236.1598122290731; Sat, 22 Aug 2020 11:51:30 -0700 (PDT) MIME-Version: 1.0 References: <1381759926.21710099.1597158389614.JavaMail.zimbra@karlsbakk.net> <4a7bfca8-af6e-cbd1-0dc4-feaf1a0288be@fritscher.net> <5F32F56C.7040603@youngman.org.uk> In-Reply-To: <5F32F56C.7040603@youngman.org.uk> From: Chris Murphy Date: Sat, 22 Aug 2020 12:50:50 -0600 Message-ID: Subject: Re: Recommended filesystem for RAID 6 To: Wols Lists Cc: Linux-RAID Content-Type: text/plain; charset="UTF-8" Sender: linux-raid-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-raid@vger.kernel.org On Tue, Aug 11, 2020 at 1:47 PM Wols Lists wrote: > > On 11/08/20 20:19, Michael Fritscher wrote: > > Hi, > > > > if you really want to use these tiny 2 TB HDDs - yes, RAID 6 (2x - the > > second for the backup system on a physically different location) is a > > good choice. > > > > But: If you can, buy some 8-12 TB HDDs and forget the old rusty tiny > > HDDs. You'll save a lot at the system - and power. > > > I'm looking at one of these ... > https://www.amazon.co.uk/Seagate-ST8000DM004-Barracuda-internal-Silver/dp/B075WYBQXJ/ref=pd_ybh_a_8?_encoding=UTF8&psc=1&refRID=WF1CTS2K9RWY96D1RENJ > > Note that it IS a shingled drive, so fine for backup, much less so for > anything else. How can you tell? From the spec, I can't find anything that indicates it. Let alone which of three varieties it is. https://www.seagate.com/www-content/product-content/barracuda-fam/barracuda-new/en-us/docs/100805918d.pdf >I'm not sure whether btrfs would be a good choice or not ... Btrfs tries to write sequentially, both data and metadata, which favors SMR drives. For device managed SMR there are some likely optimizations to help avoid random writes. Top on that list is for the workload to avoid fsync. And also using mount options: longer commit time, notreelog, space_cache v2, and nossd. If the drive reports rotational in sysfs, then nossd is used by default. Space cache v2 is slated to become the default soon. For host managed SMR there are significant requirements. Including a log structured super block. https://lwn.net/Articles/806327/ Quite a lot of preparatory work has been happening before this series lands in mainline. For other file systems, I'm not sure, but my guess is using dm-zoned, basically making non-sequential writes from XFS and ext4 into sequential writes and ensuring the various alignment requirements. -- Chris Murphy