From owner-freebsd-fs@FreeBSD.ORG Thu Dec 30 16:54:43 2010 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 26E9E1065696 for ; Thu, 30 Dec 2010 16:54:43 +0000 (UTC) (envelope-from freebsd-fs@m.gmane.org) Received: from lo.gmane.org (lo.gmane.org [80.91.229.12]) by mx1.freebsd.org (Postfix) with ESMTP id A29A08FC1D for ; Thu, 30 Dec 2010 16:54:42 +0000 (UTC) Received: from list by lo.gmane.org with local (Exim 4.69) (envelope-from ) id 1PYLlx-0006dP-CV for freebsd-fs@freebsd.org; Thu, 30 Dec 2010 17:54:41 +0100 Received: from host-174-44-170-66.hln-mt.client.bresnan.net ([174.44.170.66]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Thu, 30 Dec 2010 17:54:41 +0100 Received: from dsamms by host-174-44-170-66.hln-mt.client.bresnan.net with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Thu, 30 Dec 2010 17:54:41 +0100 X-Injected-Via-Gmane: http://gmane.org/ To: freebsd-fs@freebsd.org From: David Samms Date: Thu, 30 Dec 2010 09:54:28 -0700 Lines: 64 Message-ID: References: <4D1BCE34.4090601@nw-ds.com> <20101230085723.GA38391@tolstoy.tols.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Complaints-To: usenet@dough.gmane.org X-Gmane-NNTP-Posting-Host: host-174-44-170-66.hln-mt.client.bresnan.net User-Agent: Mozilla/5.0 (X11; U; FreeBSD amd64; en-US; rv:1.9.1.16) Gecko/20101228 Thunderbird/3.0.11 In-Reply-To: <20101230085723.GA38391@tolstoy.tols.org> Subject: Re: 8.2-RC1 and ZFS X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 30 Dec 2010 16:54:43 -0000 On 12/30/10 01:57, Marco van Tol wrote: > On Wed, Dec 29, 2010 at 05:11:32PM -0700, David Samms wrote: >> I gave ZFS a try again this afternoon and immediately came across what I >> would consider a problem. Simply running dd causes such IO contention >> that a GUI desktop is unusable and MP3s stop playing. The problem is >> very repeatable, just run dd if=/dev/zero of=big bs=1m count=6400 >> >> System is amd64, source updated Dec 27. Default ZFS parameters. (no >> tuning). With the same system but UFS+s dd causes no problems. > > Check out this mail from Jeremy Chadwick from December 28th in > freebsd-stable@. > http://docs.freebsd.org/cgi/getmsg.cgi?fetch=312384+0+current/freebsd-stable > > I think specifically the comments and tweaks regarding > vfs.zfs.txg.timeout="5" and vfs.zfs.txg.write_limit_override=1073741824 > should be usefull for you. :-) > > I'm intentionally not touching the subject why you see what you do > without tuning. I'm sure there are a great bunch of different > situations for which the defaults are the way they are. > > :-) > > Marco van Tol > Marco, thank you for your reply. Jeremy, thank you for your tuning suggestions. It does appear that the default setting for ZFS are NOT well suited for a single drive setup. Based on Jeremy's suggestions I made the following changes from the defaults: vfs.zfs.txg.timeout="5" vfs.zfs.txg.write_limit_override=268435456 # (System has 4G of RAM) kern.maxvnodes=250000 I tested both UFS+s and ZFS for desktop usability while running "dd" to create IO contention. System has two identical 300G WD drives that are about 4 years old. For testing I switch at boot between the drives, one is ZFS the other UFS+s. Test was performed using XFCE4 with xmms playing MP3s while "dd" was creating a large file and OpenOffice was launching. ZFS ---------------------------------------------------------------------- %dd if=/dev/zero of=big bs=1m count=6400 6710886400 bytes transferred in 177.418146 secs (37825254 bytes/sec) openoffice startup about 185 sec No MP3 skips XFCE4 popup menus took 1-3 seconds to appear UFS+s ---------------------------------------------------------------------- dd if=/dev/zero of=big bs=1m count=6400 6710886400 bytes transferred in 165.061623 secs (40656855 bytes/sec) openoffice startup about 185 sec No MP3 skips XFCE4 popup menus took 5-25 seconds to appear While dd IO was slower with the new ZFS parameters, the desktop was very usable, and its responsiveness was better than USF+s. I will be upgrading to ZFSv28 and repeating this rudimentary desktop usability test.