From owner-freebsd-current@FreeBSD.ORG Wed Mar 30 20:37:38 2005 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 929BE16A4CE for ; Wed, 30 Mar 2005 20:37:38 +0000 (GMT) Received: from pi.codefab.com (pi.codefab.com [199.103.21.227]) by mx1.FreeBSD.org (Postfix) with ESMTP id 5130A43D3F for ; Wed, 30 Mar 2005 20:37:38 +0000 (GMT) (envelope-from cswiger@mac.com) Received: from localhost (localhost [127.0.0.1]) by pi.codefab.com (Postfix) with ESMTP id C5F785DC9; Wed, 30 Mar 2005 15:37:37 -0500 (EST) Received: from pi.codefab.com ([127.0.0.1]) by localhost (pi.codefab.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 43907-06; Wed, 30 Mar 2005 15:37:37 -0500 (EST) Received: from [192.168.1.3] (pool-68-161-53-96.ny325.east.verizon.net [68.161.53.96]) by pi.codefab.com (Postfix) with ESMTP id BB4B05DA3; Wed, 30 Mar 2005 15:37:36 -0500 (EST) Message-ID: <424B0DF2.8090802@mac.com> Date: Wed, 30 Mar 2005 15:37:06 -0500 From: Chuck Swiger Organization: The Courts of Chaos User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.5) Gecko/20041217 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Martin Nilsson References: <20050330191824.4c08acc6.aka@veco.ru> <20050330090813.B64732@carver.gumbysoft.com> <424B0614.5000902@gneto.com> In-Reply-To: <424B0614.5000902@gneto.com> X-Enigmail-Version: 0.90.0.0 X-Enigmail-Supports: pgp-inline, pgp-mime Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-Virus-Scanned: amavisd-new at codefab.com cc: freebsd-current@FreeBSD.org Subject: Re: ciss(4): speed degradation for Compaq Smart Array [edited] X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 30 Mar 2005 20:37:38 -0000 Martin Nilsson wrote: [ ... ] > What is wrong with using dd to measure max read/write bandwith of the > controller-disk system? Nothing-- it's fine. There are people around here who have very strong viewpoints with regard to accurate, reproducable testing. Their suggestions are worth paying attention to, but there is some level of nitpicking going on about just what it is you're testing when you run such-and-such a command. > On a modern disk this should give numbers in the vicinity of 50MB/s at > the beginning of the disk. This tells me in seconds if there is > something wrong with the controller, cable, disk (or FreeBSD driver). Absolutely, you're doing a sanity check on the hardware, and seeing whether the numbers are roughly what they should be. The difference between a scientist and an engineer is that the latter *doesn't* want to reproduce the sparks when something shorts out just to obtain a standard deviation. -- -Chuck