From owner-freebsd-questions@FreeBSD.ORG Thu Mar 11 19:08:46 2010 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 87964106564A for ; Thu, 11 Mar 2010 19:08:46 +0000 (UTC) (envelope-from mahlerrd@yahoo.com) Received: from web51002.mail.re2.yahoo.com (web51002.mail.re2.yahoo.com [206.190.38.133]) by mx1.freebsd.org (Postfix) with SMTP id 2B2E28FC14 for ; Thu, 11 Mar 2010 19:08:45 +0000 (UTC) Received: (qmail 32448 invoked by uid 60001); 11 Mar 2010 19:08:45 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.com; s=s1024; t=1268334525; bh=KWv9AiWDMO2J/UGykjnaCl5zp8fp/UIMR0We/a0wJLY=; h=Message-ID:X-YMail-OSG:Received:X-Mailer:References:Date:From:Reply-To:Subject:To:In-Reply-To:MIME-Version:Content-Type; b=QJklzIdSxDe2K47fkiZPJXDEpaMsZTIt7Mamuz3rXYlUT9wWC5YRUaU21Gv/vqtLS2g1MwBP2gtknu9+t8nf4WcYE3MjXjp3ds4lN0Lp8q0vCM/TxSHVndd5svjCG/SFAAgHy0q3dtcftehUUql708qcsda+y+Lup6yphvk9TuE= DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=Message-ID:X-YMail-OSG:Received:X-Mailer:References:Date:From:Reply-To:Subject:To:In-Reply-To:MIME-Version:Content-Type; b=OlfbinvInl2NlXal4AlMDZu2Y9APOZUH6IuH7tYjF8nN6MnnCZvqLksAswBe2CXSzACFI6ztRuVK/qpA7QnPhCQ0LuRmMk+/JF0v+1O6gyqo+vKmmqcCpgWxochA3k6pinewxbfzd7YVNK+cjDqhMCAtKhnmUxCQfQF5570HxEA=; Message-ID: <339129.31373.qm@web51002.mail.re2.yahoo.com> X-YMail-OSG: aE7Sq54VM1kJzOSWDhf.6tu8ejxMVbJZrvdn3gjzMKzMf1P EFpJrEDB64hkqaZFgYIHdjh5sQKmeCvyzxG1Vz.vTcviTWO1qokGt6dI8GOk FAVsCaWMkSSmrB2zea3aHUdPGrz31F0Rz0z4D9elXBcts3MR9Csm.ovi5p68 Cpukj6KWurO0aDSK_zcb7Uo6KP4_y4kcUqyPxdcBZIqxHe.Nl.LPoNf9sAmL HfIvEAzo6XvnrnXSwDZUtZnz9ZCHlyQn3rzHo3_wIerqCpUQ5DBwtFUxPbWc fEjOWo5hej62Q3rklWv4n4RN1kbkIW8B1Xad9eP6qlDtdukIbH69lUrOswNt FYQXzUpdskeOskB0lufNzNfVDZ99sdEEpJQ-- Received: from [208.95.208.226] by web51002.mail.re2.yahoo.com via HTTP; Thu, 11 Mar 2010 11:08:45 PST X-Mailer: YahooMailRC/300.3 YahooMailWebService/0.8.100.260964 References: <4B980792.3050103@eskk.nu> <4B981934.9090904@comcast.net> <4B98CA26.4050609@eskk.nu> <20100311175307.GA4528@dan.emsphone.com> Date: Thu, 11 Mar 2010 11:08:45 -0800 (PST) From: Richard Mahlerwein To: freebsd-questions@freebsd.org In-Reply-To: <20100311175307.GA4528@dan.emsphone.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Subject: Re: Does compression on zfs pool affect performance? .......WAS, Re: Silicon Image SiI 3124 and 3132 RAID controllers X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: Richard Mahlerwein List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 11 Mar 2010 19:08:46 -0000 >----- Original Message ---- >From: Dan Nelson >In the last episode (Mar 11), Leslie Jensen said: >> The solution for me was to create a raidz which gave me the same amount of >> space. Now I wonder, should I enable compression? Will it affect >> performance? > >The default lzjb compression is very fast and won't consume much CPU. If >you have lots of easily-compressabe data it should improve performance. In informal testing I have found it depends on a lot of factors but is often a net gain. For instance, writes during testing in a VM running FBSD8 w/ ZFS writing to an attached single test "drive" on my not-terribly-fast XP laptop showed a significant improvement when I enabled compression on an FS, jumping from about 5 MB/s to easily 8+ MB/s. In testing at work on a FBSD8 guest on an ESX3.5 host running on a blade backed by a lightly loaded set of 24 15krpm drives, I found enabling compression didn't change much unless I tossed more than a single processor at it, at which point the gains were more tangible though not spectacular. I would suspect that it depends on the ratio of the speed of your CPU to the speed of your hard disk subsystem. Faster CPUs with slower disks will benefit more, slow CPUs with fast disks may even slow down. Obviously, what constitutes "Fast" and "Slow" is the big sticking point. :)