From owner-freebsd-questions Thu Jun 13 07:58:19 1996 Return-Path: owner-questions Received: (from root@localhost) by freefall.freebsd.org (8.7.5/8.7.3) id HAA28982 for questions-outgoing; Thu, 13 Jun 1996 07:58:19 -0700 (PDT) Received: from relay-2.mail.demon.net (disperse.demon.co.uk [158.152.1.77]) by freefall.freebsd.org (8.7.5/8.7.3) with SMTP id HAA28973 for ; Thu, 13 Jun 1996 07:58:06 -0700 (PDT) Received: from post.demon.co.uk ([158.152.1.72]) by relay-2.mail.demon.net id aj19453; 13 Jun 96 14:22 +0100 Received: from longacre.demon.co.uk ([158.152.156.24]) by relay-3.mail.demon.net id ab11110; 13 Jun 96 13:43 +0100 From: Michael Searle Message-ID: To: questions@freefall.freebsd.org Subject: Re: Adaptec2940UW vs. BusLogicBT-958 (opinions?) References: <199606121658.JAA16509@freefall.freebsd.org> Date: Thu, 13 Jun 1996 12:29:38 BST X-Mailer: Offlite 0.09 / Termite Internet for Acorn RISC OS Sender: owner-questions@FreeBSD.ORG X-Loop: FreeBSD.org Precedence: bulk owner-questions-digest@freefall.freebsd.org wrote: > It's not too hard to conceive of hardware which would fill > 10 MB/s. > But the application is another matter. > If you want to strip real time uncompressed video, you probably need it. > If you're in the lab and need to do some kind of data acquisition you > might need it. But running a busy web/news/mail/other-inet-application > server doesn't - it needs lots of ios/sec, not lots of bandwidth. And a > fast scsi channel can request just as many random seeks/sec as a UW bus. > Again I'll challenge people to run iozone against either a MFS (am > based) file system or just small files which fit within the disk cache > system. If you can only write to *ram* at 10-20 MB/sec do you think > it'll write to a scsi (UW) channel any faster? IOZONE: Performance Test of Sequential File I/O -- V2.01 (10/21/94) By Bill Norcott Operating System: FreeBSD 2.x -- using fsync() Send comments to: b_norcott@xway.com IOZONE writes a 1 Megabyte sequential file consisting of 128 records which are each 8192 bytes in length. It then reads the file. It prints the bytes-per-second rate at which the computer can read and write files. Writing the 1 Megabyte file, 'iozone.tmp'...0.679688 seconds Reading the file...0.023438 seconds IOZONE performance measurements: 1542732 bytes/second for writing the file 44739242 bytes/second for reading the file The test completed too quickly to give a good result You will get a more precise measure of this machine's performance by re-running IOZONE using the command: iozone 28 (i.e., file size = 28 megabytes) Although iozone seems very inaccurate at such high speeds, sometimes I get 33MB/s, sometimes 44MB/s, but never anything in between. I guess that 0.023438 seconds isn't really accurate to 1us, more like 1/128 second (as the 33MB/s give 0.03125 (1/32) seconds). And this was done on a P166. -- Michael Searle - searle@longacre.demon.co.uk