From owner-freebsd-fs@FreeBSD.ORG Wed Oct 12 16:51:29 2011 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 A04AC1065670 for ; Wed, 12 Oct 2011 16:51:29 +0000 (UTC) (envelope-from jdc@koitsu.dyndns.org) Received: from qmta03.westchester.pa.mail.comcast.net (qmta03.westchester.pa.mail.comcast.net [76.96.62.32]) by mx1.freebsd.org (Postfix) with ESMTP id 4D3BB8FC08 for ; Wed, 12 Oct 2011 16:51:28 +0000 (UTC) Received: from omta20.westchester.pa.mail.comcast.net ([76.96.62.71]) by qmta03.westchester.pa.mail.comcast.net with comcast id jqFl1h0061YDfWL53srVcg; Wed, 12 Oct 2011 16:51:29 +0000 Received: from koitsu.dyndns.org ([67.180.84.87]) by omta20.westchester.pa.mail.comcast.net with comcast id jsrT1h00q1t3BNj3gsrU3c; Wed, 12 Oct 2011 16:51:29 +0000 Received: by icarus.home.lan (Postfix, from userid 1000) id AA4B8102C1D; Wed, 12 Oct 2011 09:51:26 -0700 (PDT) Date: Wed, 12 Oct 2011 09:51:26 -0700 From: Jeremy Chadwick To: freebsd-fs@freebsd.org Message-ID: <20111012165126.GA26562@icarus.home.lan> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Subject: Re: ZFS/compression/performance 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: Wed, 12 Oct 2011 16:51:29 -0000 On Wed, Oct 12, 2011 at 09:37:10AM -0700, David Brodbeck wrote: > On Wed, Oct 12, 2011 at 5:02 AM, Johannes Totz wrote: > > > I just did a simple write test yesterday: > > > > 1) 6 MB/sec for gzip, 1.36x ratio > > 2) 34 MB/sec for lzjb, 1.23x ratio > > > > I'll stick with lzjb. It's good enough to get rid of most of the > > redundancy and speed is acceptable. > > > > That's what we use on our text-heavy filesystems on our OpenSolaris server. > (We work with large text corpora, so we have hundreds of gigabytes of pure > text.) My benchmarks showed the performance hit for reads is nonexistent > when viewed over NFS, and the performance hit for writes is relatively > small...plus we don't write to that filesystem much. We see about 1.5x > compression overall, with a little over 2x on some datasets that are > particularly compressible. That might be the case on OpenSolaris but the performance hit on FreeBSD RELENG_8 is very high -- enough that enabling compression (using the defaults) causes stalls when I/O occurs (easily noticeable across SSH; characters are delayed/stalled (not buffered)), etc.. The last time I tried it on RELENG_8 was right after ZFSv28 was MFC'd. If things have improved I can try again (I don't remember seeing any commits that could affect this), or if people really think changing the compression model to lzjb will help. Another point: I haven't tinkered with compression on our Solaris 10 machines at work so I don't know if it performs better, equal, or worse than FreeBSD or OpenSolaris. -- | Jeremy Chadwick jdc at parodius.com | | Parodius Networking http://www.parodius.com/ | | UNIX Systems Administrator Mountain View, CA, US | | Making life hard for others since 1977. PGP 4BD6C0CB |