From owner-freebsd-fs@FreeBSD.ORG Mon Apr 5 19:18:21 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 5C205106566B for ; Mon, 5 Apr 2010 19:18:21 +0000 (UTC) (envelope-from nekoexmachina@gmail.com) Received: from mail-fx0-f209.google.com (mail-fx0-f209.google.com [209.85.220.209]) by mx1.freebsd.org (Postfix) with ESMTP id DCF798FC12 for ; Mon, 5 Apr 2010 19:18:20 +0000 (UTC) Received: by fxm1 with SMTP id 1so2920941fxm.13 for ; Mon, 05 Apr 2010 12:18:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:date:from:to:cc:subject :message-id:references:mime-version:content-type:content-disposition :in-reply-to:user-agent; bh=UXgU3/+E2E8Y1+uFmXc7MLMfArrRs5KRCtiV7hjBzxg=; b=E7n+XRq55HzI57et1dPSCrgFZByWNnBeAyP47m2eSnJdT6QV1k0Zpl5EQ00pIjyeZo F4b8XphIhE3LKABmRX370z/GNZKHl/OoR5fl+BukSoj04pgKW2HYpEMHk7a1F2HhaB0c UMwalQ0AZp2Ci3qVpSQHTfeB/QVZItqk/rQTs= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=uKBn5uouultI2HbW/p2tMTfxblLvDsAu3fx0JPM3pwgKRQ0GtZySrc9M4QimST/Gpd EAPg7HoHOq2y+Sn89orPK1US7fZKiFGeXRMTCw4VEpChfaOYth8tWbVNcMGNTEib0Q76 IIfnCLXpDPdxn8qeThia6ndgtuuOR3p6N5LY4= Received: by 10.223.1.146 with SMTP id 18mr6173509faf.53.1270495099702; Mon, 05 Apr 2010 12:18:19 -0700 (PDT) Received: from localhost ([188.134.12.208]) by mx.google.com with ESMTPS id 21sm27080794fks.53.2010.04.05.12.18.18 (version=TLSv1/SSLv3 cipher=RC4-MD5); Mon, 05 Apr 2010 12:18:19 -0700 (PDT) Date: Mon, 5 Apr 2010 23:16:43 +0400 From: Mikle Krutov To: Bob Friesenhahn Message-ID: <20100405191643.GA5996@takino.homeftp.org> References: <20100405073059.GA68655@icarus.home.lan> <20100405095245.GA1152@takino.homeftp.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) Cc: freebsd-fs@freebsd.org Subject: Re: Fwd: Re: Strange ZFS 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: Mon, 05 Apr 2010 19:18:21 -0000 On Mon, Apr 05, 2010 at 12:24:15PM -0500, Bob Friesenhahn wrote: > On Mon, 5 Apr 2010, Mikle Krutov wrote: > > Any information i could provide to help us know what's the source of the problem? > > The svc_t value I saw posted in one of your mails was outrageously > large. I suggest running > > iostat -x 30 > > while doing long-duration write and see what the actual values are. > It seems likely that you are overrunning what your controller or disk > is capable of handling and this is creating an I/O backlog which is > far greater than what it would be if zfs had queued fewer > simultaneous requests. > > It may be that tuning zfs_vdev_max_pending to a small value may help > keep your controller from being overloaded. > > Bob > -- > Bob Friesenhahn > bfriesen@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/ > GraphicsMagick Maintainer, http://www.GraphicsMagick.org/ With copeing from one disk to another (e.g. reading from ad12), svc_t is pretty large (2.0-3.5 on target disk v.s. 11 in the beginning - up to 42 to the end on ad12). For writing it is ~20 in the beginning, and pretty fast it enlarges to 200 Also, if it was the overrun of hdd/controller capability, by my mind, io should have been very slow for some amount of time, while zfs is flushing the data from mem to the hdd, and then it should go up to normal 60MB/s. It does not happen, e.g. if i'm trying to write something just after reboot with no data to be flushed from my mem speed is already 2-6MB/s But still, i've tried to set vfs.zfs.vdev.max_pending to 8 and 4, it did not help. -- Wbr, Krutov Mikle