From owner-freebsd-questions@FreeBSD.ORG Sun Apr 25 11:51:06 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 6BA97106566B for ; Sun, 25 Apr 2010 11:51:06 +0000 (UTC) (envelope-from amsibamsi@gmail.com) Received: from fg-out-1718.google.com (fg-out-1718.google.com [72.14.220.159]) by mx1.freebsd.org (Postfix) with ESMTP id EE61C8FC17 for ; Sun, 25 Apr 2010 11:51:05 +0000 (UTC) Received: by fg-out-1718.google.com with SMTP id 22so1081689fge.13 for ; Sun, 25 Apr 2010 04:51:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:message-id:date:from :user-agent:mime-version:to:subject:x-enigmail-version:content-type :content-transfer-encoding; bh=FS13SWe9aF97pJV0hgCFp70kBzuQ5lMkpQbWym5IhxE=; b=TfL+Y+MySOxzOMp4nbyhXZpVoWG0y+Vry/9BPEYv+uuI1IYRc7lSuGoZzX4u19+ffE tuH9EkYNx/jidzznDOOych/BgemdAIm8vZL3Bav+r6rXUMCEYIAvHdtJ/6zI2OSUfEro SyJCtccjG4IjLqFRAVWUWBhKHPQIx2K1zCWIo= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:user-agent:mime-version:to:subject :x-enigmail-version:content-type:content-transfer-encoding; b=ZWy1Hhb+1Lan7tvg8fqrqjTk71/AuQKin9nj67t0fjzqB6iRg8FcjiKZYYChKSDeDe MozeYvZCjWnqtdzo10qWtsw8K9tikyLyPuqvHORY+QSGvz1h8Y2NsjKoRcPIzrNdcNih UyRzketWFTSZsHjJZ25YbATq2Wr0ZuMTnf0uw= Received: by 10.86.221.34 with SMTP id t34mr4189208fgg.36.1272196260913; Sun, 25 Apr 2010 04:51:00 -0700 (PDT) Received: from hulk.l.ttyv0.net (80-219-19-168.dclient.hispeed.ch [80.219.19.168]) by mx.google.com with ESMTPS id 3sm1831359fge.15.2010.04.25.04.51.00 (version=SSLv3 cipher=RC4-MD5); Sun, 25 Apr 2010 04:51:00 -0700 (PDT) Message-ID: <4BD42CA4.8050201@gmail.com> Date: Sun, 25 Apr 2010 13:51:00 +0200 From: Anselm Strauss User-Agent: Mozilla/5.0 (X11; U; FreeBSD amd64; en-US; rv:1.9.1.9) Gecko/20100424 Thunderbird/3.0.4 MIME-Version: 1.0 To: freebsd-questions@freebsd.org X-Enigmail-Version: 1.0.1 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: ZFS scheduling X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 25 Apr 2010 11:51:06 -0000 Hi, I noticed that my system gets very slow when I'm doing some simple but intense ZFS operations. For example, I move about 20 Gigabytes of data from one data set to another on the same pool, which is a RAIDZ of 3 500 GB SATA disks. The operations itself runs fast, but meanwhile other things get really slow. E.g. opening a application takes 5 times as long as before. Also simple operations like 'ls' stall for some seconds which they did never before. It already changed a lot when I switched from RAIDZ to a mirror with only 2 disks. Memory and CPU don't seem to be the issue, I have a quad-core CPU and 8 GB RAM. I can't get rid of the idea that this has something to do with scheduling. The system is absolutely stable and fast. Somehow small I/O operations on ZFS seem to have it very difficult to make it through when other bigger ones are running. Maybe this has something to do with tuning? I know my system information is very incomplete, and there could be a lot of causes. But anybody knows if this could be an issue with ZFS itself? Thanks, Anselm