From owner-freebsd-hardware Wed Aug 28 21:33:23 1996 Return-Path: owner-hardware Received: (from root@localhost) by freefall.freebsd.org (8.7.5/8.7.3) id VAA13305 for hardware-outgoing; Wed, 28 Aug 1996 21:33:23 -0700 (PDT) Received: from GndRsh.aac.dev.com (GndRsh.aac.dev.com [198.145.92.241]) by freefall.freebsd.org (8.7.5/8.7.3) with SMTP id VAA13283 for ; Wed, 28 Aug 1996 21:33:14 -0700 (PDT) Received: (from rgrimes@localhost) by GndRsh.aac.dev.com (8.6.12/8.6.12) id VAA00814; Wed, 28 Aug 1996 21:33:05 -0700 From: "Rodney W. Grimes" Message-Id: <199608290433.VAA00814@GndRsh.aac.dev.com> Subject: Re: DAT or removable device? To: richard@pegasus.com (Richard Foulk) Date: Wed, 28 Aug 1996 21:33:05 -0700 (PDT) Cc: freebsd-hardware@FreeBSD.org In-Reply-To: <199608290314.RAA08700@pegasus.com> from Richard Foulk at "Aug 28, 96 05:14:14 pm" X-Mailer: ELM [version 2.4ME+ PL11 (25)] 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 > } * Supposedly, the NCR/Symbios-based cards don't perform well under heavy > } loads, such as when you have three or more disks being accessed > } *simultaneously*. This isn't an issue for most people. > > This appears to be hearsay. No numbers have been presented. This is not hearsay. I can't give you numbers that mean a whole lot, they are from running a PCI bus analyzer. The busier a NCR 53Cxxx gets the more PCI bandwidth, and host memory bandwidth gets eaten up. And I am not talking about the data transfer bandwidth (though that is the majority of the PCI traffic), but the microcode fetch bandwidth. I do not recommend running lots of drives or lots of 53C8xx's in a machine for that very reason, UNLESS lower cost is an objective and performance can suffer by reducing the cost. -- Rod Grimes rgrimes@gndrsh.aac.dev.com Accurate Automation Company Reliable computers for FreeBSD