Date: Mon, 17 Nov 1997 23:35:26 +0100 From: j@uriah.heep.sax.de (J Wunsch) To: freebsd-scsi@FreeBSD.ORG (FreeBSD SCSI) Cc: dburr@POBoxes.com (Donald Burr) Subject: Re: Status of Adaptec AHA-2920? Message-ID: <19971117233526.WM25968@uriah.heep.sax.de> In-Reply-To: <Pine.LNX.3.95.971116100952.1461A-100000@donaldburr.dyn.ml.org>; from Donald Burr on Nov 16, 1997 10:28:39 -0800 References: <Pine.BSF.3.95.971116035327.1064A-100000@luke.cpl.net> <Pine.LNX.3.95.971116100952.1461A-100000@donaldburr.dyn.ml.org>
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As Donald Burr wrote: > Hrm, the whole point of my msg was that price is my main factor. I don't Then the NCR should be good for you. :) > particularly care about busmaster, booting off the card, etc. All I'm > ever planning to drive with this card is a CD-ROM and a Jaz drive, and I > don't particularly care about high performance on these devices (the JAZ > is only used for archival storage, and I don't care if it takes 8 seconds > vs. 4 to move a .tar.gz file onto it, etc.). I've got (E)IDE HD's in my > system that I'm perfectly happy with. Anyway, it's only a 5x86-133. A slow processor needs busmaster DMA much more than a faster CPU. ;-) The point is that PIO transfers bind your valuable CPU resources that could be used otherwise simultaneously when using DMA. > ever upgrade to my Pentium II dream system, I'll surely have a bit more > cash to play with, so then I'll get the 2940 for performance. Btw., it's an old but equally wrong hype that something like an AHA2940 were faster than the NCR chips. (Of course, assuming similar environment, i.e. compare the NCR 53c810 with a plain AHA2940, and the 53c875 with an AHA2940UW.) The Adaptec is way more expensive (and has some other interesting features like on-board memory to remember the device configuration), but it's not faster. The worst point of the NCR is indeed the BIOS support, but you'd be surprised to find out how many BIOSes actually do support it, without announcing this fact anywhere. A colleague yesterday confirmed this again, for a plain standard Award BIOS. > So I guess my original question stands: is the AHA-2920 supported by any > version of FreeBSD (or any patch thereof)? There's some rather preliminary support on the FreeBSD 2.2.5 CD-ROM, in /xperimnt. The driver leaves quite a number of things to be desired (in short, it doesn't fit quite right into the FreeBSD tree structure, since it migrated from NetBSD via the PAO distribution), so i could not make up my mind to import it into the FreeBSD tree. As far as i've observed, it's rather stable. However, given the choice, i would always prefer the NCR controllers over an AHA2920. -- cheers, J"org joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ -- NIC: JW11-RIPE Never trust an operating system you don't have sources for. ;-)
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