From owner-freebsd-stable@FreeBSD.ORG Wed Jan 14 05:17:22 2004 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id D7E9016A4CE for ; Wed, 14 Jan 2004 05:17:22 -0800 (PST) Received: from mail.rotfl.com.au (eth1779.sa.adsl.internode.on.net [150.101.235.242]) by mx1.FreeBSD.org (Postfix) with ESMTP id 7F1AA43D46 for ; Wed, 14 Jan 2004 05:17:20 -0800 (PST) (envelope-from Phil@Kernick.org) Received: from undisclosed by mail.rotfl.com.au (Postfix) with ESMTP id 690EB7482E; Wed, 14 Jan 2004 23:47:19 +1030 (CST) Received: from mail.rotfl.com.au ([127.0.0.1]) by localhost (mail.rotfl.com.au [127.0.0.1]) (amavisd-new, port 10024) with LMTP id 84410-06; Wed, 14 Jan 2004 23:47:16 +1030 (CST) Received: from undisclosed by mail.rotfl.com.au (Postfix) with ESMTP id CB8517482C; Wed, 14 Jan 2004 23:47:16 +1030 (CST) Message-ID: <4005415C.6090102@Kernick.org> Date: Wed, 14 Jan 2004 23:47:16 +1030 From: Phil Kernick User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.6b) Gecko/20031208 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Ari Suutari References: <200401141453.50150.ari@suutari.iki.fi> <16389.15817.322098.577889@raw.grenland.fast.no> <200401141511.30958.ari@suutari.iki.fi> In-Reply-To: <200401141511.30958.ari@suutari.iki.fi> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-Virus-Scanned: by amavisd-new at rotfl.com.au cc: freebsd-stable@freebsd.org cc: Raymond Wiker Subject: Re: Adaptect raid performance with FreeBSD X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 14 Jan 2004 13:17:23 -0000 A note from the dump(8) man page... Currently, physio(9) slices all requests into chunks of 64 KB. There- fore, it is impossible to use a larger output block size, so dump will prevent this from happening. Same thing likely happens with dd, so bigger than 64k doesn't ever help. Phil. Ari Suutari wrote: > On Wednesday 14 January 2004 15:02, Raymond Wiker wrote: > >>Ari Suutari writes: >> > dd if=/dev/rda1s1a of=/dev/null bs=1m count=100 >> > 100+0 records in >> > 100+0 records out >> > 104857600 bytes transferred in 4.193832 secs (25002814 bytes/sec) >> > >> > So, I get only about 25MB/s. Shouldn't I be getting something >> > like 70 MB/s, or even more since there are two disks that >> > can server read requests ? >> >> Have you tried other block sizes? I think you may be able to >>get better results by going to a lower block size (e.g, 64k instead of >>1m). Some experimentation will show which block size(s) work best. > > > > I tried with 32k, 64k, 256k and 512k. Speed is about the same > with every block size. Block sizes less than 32k seem to give > even worse performance. > > Ari S. > -- _-_|\ Phil Kernick E-Mail: Phil@Kernick.org / \ ROTFL Enterprises Mobile: 041 61 ROTFL \_.-*_/ v Humourist, satirist, and probably a few more 'ists to boot!