From owner-freebsd-fs@FreeBSD.ORG Fri Dec 31 02:58:52 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 51FC7106566C for ; Fri, 31 Dec 2010 02:58:52 +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 D25338FC0C for ; Fri, 31 Dec 2010 02:58:51 +0000 (UTC) Received: from list by lo.gmane.org with local (Exim 4.69) (envelope-from ) id 1PYVCc-0006YE-Ek for freebsd-fs@freebsd.org; Fri, 31 Dec 2010 03:58:50 +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 ; Fri, 31 Dec 2010 03:58:50 +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 ; Fri, 31 Dec 2010 03:58:50 +0100 X-Injected-Via-Gmane: http://gmane.org/ To: freebsd-fs@freebsd.org From: David Samms Date: Thu, 30 Dec 2010 19:58:37 -0700 Lines: 93 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: 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: Fri, 31 Dec 2010 02:58:52 -0000 On 12/30/10 09:54, David Samms wrote: > 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. The same test with ZFSv28 and ZFSv28 + tuning ZFSv28 ---------------------------------------------------------------------- dd if=/dev/zero of=big bs=1m count=6400 6710886400 bytes transferred in 158.205268 secs (42418855 bytes/sec) OpenOffice 197sec MP3 skips XFCE4 popup menus took 5-15 seconds to appear ZFSv28 + tuning --vfs.zfs.txg.timeout="5" --vfs.zfs.txg.write_limit_override=268435456 --kern.maxvnodes=250000 ---------------------------------------------------------------------- dd if=/dev/zero of=big bs=1m count=6400 6710886400 bytes transferred in 167.316444 secs (40108947 bytes/sec) OpenOffice 190sec No MP3 skips during "dd", but one skip while OpenOffice was starting XFCE4 popup menus took 2-13 seconds to appear