From owner-freebsd-hardware Tue Aug 20 18:00:42 1996 Return-Path: owner-hardware Received: (from root@localhost) by freefall.freebsd.org (8.7.5/8.7.3) id SAA21823 for hardware-outgoing; Tue, 20 Aug 1996 18:00:42 -0700 (PDT) Received: from MindBender.HeadCandy.com (root@mindbender.headcandy.com [199.238.225.168]) by freefall.freebsd.org (8.7.5/8.7.3) with ESMTP id SAA21817 for ; Tue, 20 Aug 1996 18:00:29 -0700 (PDT) Received: from localhost.HeadCandy.com (michaelv@localhost.HeadCandy.com [127.0.0.1]) by MindBender.HeadCandy.com (8.7.5/8.7.3) with SMTP id RAA10672; Tue, 20 Aug 1996 17:56:54 -0700 (PDT) Message-Id: <199608210056.RAA10672@MindBender.HeadCandy.com> X-Authentication-Warning: MindBender.HeadCandy.com: Host michaelv@localhost.HeadCandy.com [127.0.0.1] didn't use HELO protocol To: "Rodney W. Grimes" cc: jas@flyingfox.com (Jim Shankland), freebsd-hardware@freebsd.org Subject: Re: SCSI again: Asus SC200 vs. Adaptec 2940 In-reply-to: Your message of Tue, 20 Aug 96 16:03:31 -0700. <199608202303.QAA08500@GndRsh.aac.dev.com> Date: Tue, 20 Aug 1996 17:56:48 -0700 From: "Michael L. VanLoon -- HeadCandy.com" Sender: owner-hardware@freebsd.org X-Loop: FreeBSD.org Precedence: bulk >> A follow-up question, that I hope is of general interest: how does >> the SC200 stack up against the Adaptec 2940U? The SC200 is quite a >The line between when to switch from a 53C810 (I prefer to refer to >it by that number, as there are others besides the SC-200) to an >AHA2940U is real wide, and kinda grey, but here are some of the >things I use in helping clients decide this issue. [Some suggestions deleted...] I have been doing some testing over the last week or so between a BusLogic BT956c (PCI Wide, but not Ultra) and an Adaptec 2940UW. Unfortunately, I did not have an NCR 53c810 controller to mix in. The tests were conducted on a P5/120 (Asus P55TP4N, 512K PB cache, 32MB EDO RAM), with the controllers mentioned above, a 2GB Seagate Barracuda (ST32550N) approximately 45% full, and a 1GB Seagate Hawk (ST31200N) completely empty. Both drives support tagged-command- queuing. I tried to do at least half the tests against both drives simultaneously. I have concluded that these two SCSI controllers are almost completely equal in performance, if you don't have tagged-command-queuing. However, if you enable tagged-command-queuing in the Adaptec driver, the performance increase is *very* substantial, at least in my tests. Since the BusLogic doesn't currently have tagged-command-queuing in the bt driver, it loses this particular point. (But remember, your drives have to support it correctly, as well -- there are some older SCSI drives out there that don't support, or have buggy support. Hopefully all current drives on the market have decent support for it.) I don't know if the NCR has tagged-command-queuing support or not. If it did, I don't think I would trust it (the NCR driver is OK for workstation type stuff, as Justin pointed out, but it is known to be buggier than either the BusLogic or Adaptec drivers). >I do have to say that I have an order of magnitude more trust in the >aha2940 driver, and on my ability to get a bug fixed when I need it >(Hi Justin! Thanks for the _GREAT_ support!!) by sending the broken >hardware to Justin and giving him some time to work on it. On the other hand, the NCR is substantially cheaper than either of these two cards. And, it's reliability is decent enough to run a personal workstation. I don't think I'd run an important server on one, though. ----------------------------------------------------------------------------- Michael L. VanLoon michaelv@HeadCandy.com --< Free your mind and your machine -- NetBSD free un*x >-- NetBSD working ports: 386+PC, Mac 68k, Amiga, Atari 68k, HP300, Sun3, Sun4/4c/4m, DEC MIPS, DEC Alpha, PC532, VAX, MVME68k, arm32... NetBSD ports in progress: PICA, others... Roll your own Internet access -- Seattle People's Internet cooperative. If you're in the Seattle area, ask me how. -----------------------------------------------------------------------------