From owner-freebsd-performance@FreeBSD.ORG Tue Sep 28 05:45:41 2010 Return-Path: Delivered-To: freebsd-performance@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id DE024106566B for ; Tue, 28 Sep 2010 05:45:41 +0000 (UTC) (envelope-from mavbsd@gmail.com) Received: from mail-bw0-f54.google.com (mail-bw0-f54.google.com [209.85.214.54]) by mx1.freebsd.org (Postfix) with ESMTP id 63EA78FC12 for ; Tue, 28 Sep 2010 05:45:40 +0000 (UTC) Received: by bwz15 with SMTP id 15so5154662bwz.13 for ; Mon, 27 Sep 2010 22:45:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:sender:message-id:date:from :user-agent:mime-version:to:subject:references:in-reply-to :x-enigmail-version:content-type:content-transfer-encoding; bh=dyE1f7B50CDTv9ub6SUGOfu1q5jew1FtJ6Es0eoy67g=; b=PETMjQMLE5aVBckOaB58DmhiW4yQ80jBdjE6ZNfPuH2p9aA3zRhI6j4GHrpPX07hQk hHgDy+vvxF3/SacXcQItjUyD4aa3aSuu2+YJ0bKGIFA84nAO0e+79rmzG0ZRlqqG7UUp ZjjcuENIEsUz73UY+cxMoNW2vb2X5jkVTX6L4= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=sender:message-id:date:from:user-agent:mime-version:to:subject :references:in-reply-to:x-enigmail-version:content-type :content-transfer-encoding; b=rmRx/uwraKZIeKEA6G7dfx9McLV22aGLTUrpYhZo76Ec+XZeNmJ10qVHaw6iylhlGe 1KXlpFDh7rarEecHrIZ6n7oPLHWon0QvMlJuYMW7AuY4m/Vv6oGAfykbjLYXPvsIX8h7 hk/5baol4FNGDgf7PacGQFh95mgqeDFgR6kFU= Received: by 10.204.69.18 with SMTP id x18mr6284717bki.34.1285652740192; Mon, 27 Sep 2010 22:45:40 -0700 (PDT) Received: from mavbook.mavhome.dp.ua (pc.mavhome.dp.ua [212.86.226.226]) by mx.google.com with ESMTPS id f18sm5193495bkf.15.2010.09.27.22.45.38 (version=SSLv3 cipher=RC4-MD5); Mon, 27 Sep 2010 22:45:39 -0700 (PDT) Sender: Alexander Motin Message-ID: <4CA180FD.9050002@FreeBSD.org> Date: Tue, 28 Sep 2010 08:45:33 +0300 From: Alexander Motin User-Agent: Thunderbird 2.0.0.24 (X11/20100402) MIME-Version: 1.0 To: Stephen Sanders , freebsd-performance@freebsd.org References: In-Reply-To: X-Enigmail-Version: 0.96.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Mailman-Approved-At: Tue, 28 Sep 2010 11:19:26 +0000 Cc: Subject: Re: gstripe small transaction size X-BeenThere: freebsd-performance@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Performance/tuning List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 28 Sep 2010 05:45:41 -0000 Stephen Sanders wrote: > I'm trying a disk throughput experiment where in two 3ware raid 6's are > being put into a g_strip raid 0. > > The raid 6's are using 8 7200RPM disks. The disk transfer rate is > ~80MB/s. Using a load generation tool that is using O_DIRECT for I/O, > I've generated the following short output from iostat. Needless to say, > the write performance is a lot less than I'm expecting. > > We've modified the kernel such that our KB/t figure is closer to 512KB/t > per disk when measured without the g_strip. With g_strip turned on, the > KB/t number is more like 60KB/t. > > The question is how do I get g_stripe to write larger transactions to > the disk ? How old is your system? There was bug, fixed 8-12 months ago, making fast mode in gstripe not working on systems with increased MAXPHYS. As I understand, it is what you've changed in your kernel. -- Alexander Motin