From owner-freebsd-hackers@FreeBSD.ORG Tue Jan 15 20:55:32 2013 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.FreeBSD.org [8.8.178.115]) by hub.freebsd.org (Postfix) with ESMTP id 5A07854F for ; Tue, 15 Jan 2013 20:55:32 +0000 (UTC) (envelope-from adrian.chadd@gmail.com) Received: from mail-wi0-f179.google.com (mail-wi0-f179.google.com [209.85.212.179]) by mx1.freebsd.org (Postfix) with ESMTP id F029A7DC for ; Tue, 15 Jan 2013 20:55:31 +0000 (UTC) Received: by mail-wi0-f179.google.com with SMTP id o1so577405wic.0 for ; Tue, 15 Jan 2013 12:55:27 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:x-received:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type; bh=x8e8QgX2hlkXqxrvPqQWCL3Tp5JikLO6BtsRyaNANms=; b=lfo7JrhmYCuStq+qtUhE4xSzs+fe5h9s1N02YBAZPlGGFv2VUAWQkplMQOMxvb8Rhu 9AQC1oAQWL4NV17D3LdVdwGlJlIJl5OJP1QNqY/dqZfFdoDr4CRhSwwxFjPgfNOT0/Pa k03tGTK53pKsnQNOOXmTuVwAgALeqT9VTUNrzt+79e1U2p+Xe30PdO+fMDehBDalmEt3 7jtMsp4tTC2YMzADTAbEBq/XbNi+6vxkcWXjhBvaUMnx9I4TBK/kETNIYj42fv6SjSSw 3iHiGhWxq6wxmLxf4nyHk85zbWRwILKFFKak07YHY97hshGWTWDqqIfcqJXmdAKfQZWy N/lQ== MIME-Version: 1.0 X-Received: by 10.180.33.44 with SMTP id o12mr6055577wii.28.1358283327727; Tue, 15 Jan 2013 12:55:27 -0800 (PST) Sender: adrian.chadd@gmail.com Received: by 10.217.57.9 with HTTP; Tue, 15 Jan 2013 12:55:27 -0800 (PST) In-Reply-To: <50F5BC08.1060700@gmail.com> References: <50F5BC08.1060700@gmail.com> Date: Tue, 15 Jan 2013 12:55:27 -0800 X-Google-Sender-Auth: iErstpVOyKx9JbpMwuPsW4Vb1Q8 Message-ID: Subject: Re: IBM blade server abysmal disk write performances From: Adrian Chadd To: Karim Fodil-Lemelin Content-Type: text/plain; charset=ISO-8859-1 Cc: freebsd-hackers@freebsd.org X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 15 Jan 2013 20:55:32 -0000 Hi, You're only doing one IO at the end. That's just plain silly. There's all kinds of overhead that could show up, that would be amortized over doing many IOs. You should also realise that the raw disk IO on Linux is by default buffered, so you're hitting the buffer cache. The results aren't going to match, not unless you exhaust physical memory and start falling behind on disk IO. At that point you'll see what the fuss is about. Adrian