From owner-freebsd-questions@freebsd.org Fri Jan 22 05:19:05 2016 Return-Path: Delivered-To: freebsd-questions@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 0DF72A8C5D1 for ; Fri, 22 Jan 2016 05:19:05 +0000 (UTC) (envelope-from mason@blisses.org) Received: from phlegethon.blisses.org (phlegethon.blisses.org [50.56.97.101]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id EA2631BA8 for ; Fri, 22 Jan 2016 05:19:04 +0000 (UTC) (envelope-from mason@blisses.org) Received: from blisses.org (cocytus.blisses.org [23.25.209.73]) by phlegethon.blisses.org (Postfix) with ESMTPSA id 49B2B1493BE; Fri, 22 Jan 2016 00:19:02 -0500 (EST) Date: Fri, 22 Jan 2016 00:19:00 -0500 From: Mason Loring Bliss To: David Christensen Cc: freebsd-questions@freebsd.org Subject: Re: ZFS performance help sought Message-ID: <20160122051900.GP4538@blisses.org> References: <20160121205139.GG4538@blisses.org> <56A1B969.4020107@holgerdanske.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <56A1B969.4020107@holgerdanske.com> User-Agent: Mutt/1.5.23 (2014-03-12) X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 22 Jan 2016 05:19:05 -0000 On Thu, Jan 21, 2016 at 09:08:57PM -0800, David Christensen wrote: > 1. Have you tested the disks, cables, and controllers individually using > disk manufacturer diagnostics? E.g. for Seagate, SeaTools for DOS (bootable > CD based on FreeDOS; MS-DOS not required): Yeah. Plus, this only happens with FreeBSD, and I don't believe that Linux is quietly working around some really subtle weirdnesses in my drives. Honestly, the verification you're suggesting would be an absolutely tremendous amount of work and pretty disruptive only to highlight that the hardware is okay and FreeBSD or the way it uses ZFS is doing something odd. I did the "here, let me test the devices" dance when I discovered an OS- agnostic flaw in OpenZFS, and I'm just not going to do it again. I don't want to seem ungrateful for your time in writing up the questions, but I don't see how I can reasonably obtain the data you want. It'd be much less work to just go to a known-good Linux configuration, but that doesn't make FreeBSD better, which is a giant part of my goal in having switched back. The iostat output earlier in the thread showed a snapshot of relative performance, and I'm happy to do more diagnostics that don't involve disassembling this particular box. -- Mason Loring Bliss mason@blisses.org Ewige Blumenkraft! (if awake 'sleep (aref #(sleep dream) (random 2))) -- Hamlet, Act III, Scene I