From owner-freebsd-hardware Fri Nov 29 20:44:24 1996 Return-Path: owner-hardware Received: (from root@localhost) by freefall.freebsd.org (8.7.5/8.7.3) id UAA23290 for hardware-outgoing; Fri, 29 Nov 1996 20:44:24 -0800 (PST) Received: from dyson.iquest.net ([198.70.144.127]) by freefall.freebsd.org (8.7.5/8.7.3) with ESMTP id UAA23285; Fri, 29 Nov 1996 20:44:21 -0800 (PST) Received: (from root@localhost) by dyson.iquest.net (8.8.2/8.6.9) id XAA09675; Fri, 29 Nov 1996 23:44:09 -0500 (EST) From: "John S. Dyson" Message-Id: <199611300444.XAA09675@dyson.iquest.net> Subject: Re: Adaptec UW controller and Seagate Elite performance ? To: mango@staff.communique.net (Raul Zighelboim) Date: Fri, 29 Nov 1996 23:44:08 -0500 (EST) Cc: hackers@freefall.freebsd.org, hardware@freefall.freebsd.org In-Reply-To: from "Raul Zighelboim" at Nov 29, 96 10:28:12 pm X-Mailer: ELM [version 2.4 PL24 ME8] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-hardware@FreeBSD.ORG X-Loop: FreeBSD.org Precedence: bulk > > # bonnie -s 40 (akira, http running) > -------Sequential Output-------- ---Sequential Input-- --Random-- > -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks--- > MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU /sec %CPU > 40 3271 34.8 3085 13.0 1559 8.3 10330 97.1 44763 95.7 991.0 20.4 > > and > IOZONE performance measurements: > 2039008 bytes/second for writing the file > 34861747 bytes/second for reading the file > > It bothered me that: > 1- reading is 20 times faster than writing You are seeing the results of caching. The system remembers what is written so that it doesn't have to unnecessarily re-read the data. > > 2- 2Mbytes/s for writing seems slow, even if this was a scsi-2 and not > an > scsi fast and wide drive. > I don't know why your iozone write perf is so slow, unless you are writing 512 bytes at a time. Note also, that you might not have the write behind caching enabled on your drive. Try the following commands: # iozone auto and # iozone 40 8192 and # iozone 8192 and let me know the results. John dyson@freebsd.org