From owner-freebsd-hackers Thu Dec 5 14:22:10 1996 Return-Path: Received: (from root@localhost) by freefall.freebsd.org (8.8.4/8.8.4) id OAA09602 for hackers-outgoing; Thu, 5 Dec 1996 14:22:10 -0800 (PST) Received: from Octopussy.MI.Uni-Koeln.DE (Octopussy.MI.Uni-Koeln.DE [134.95.166.20]) by freefall.freebsd.org (8.8.4/8.8.4) with SMTP id OAA09592 for ; Thu, 5 Dec 1996 14:21:19 -0800 (PST) Received: from x14.mi.uni-koeln.de (annexr3-4.slip.Uni-Koeln.DE) by Octopussy.MI.Uni-Koeln.DE with SMTP id AA23062 (5.67b/IDA-1.5 for ); Thu, 5 Dec 1996 23:21:15 +0100 Received: (from se@localhost) by x14.mi.uni-koeln.de (8.8.4/8.6.9) id XAA00763; Thu, 5 Dec 1996 23:21:14 +0100 (CET) Message-Id: Date: Thu, 5 Dec 1996 23:21:13 +0100 From: se@freebsd.org (Stefan Esser) To: mrcpu@cdsnet.net (Jaye Mathisen) Cc: kuku@gilberto.physik.rwth-aachen.de (Christoph Kukulies), freebsd-hackers@freefall.freebsd.org Subject: Re: ccd considerations References: <199612050844.JAA17324@gilberto.physik.rwth-aachen.de> X-Mailer: Mutt 0.52 Mime-Version: 1.0 In-Reply-To: ; from Jaye Mathisen on Dec 5, 1996 13:43:28 -0800 Sender: owner-hackers@freebsd.org X-Loop: FreeBSD.org Precedence: bulk On Dec 5, mrcpu@cdsnet.net (Jaye Mathisen) wrote: > > I would think that you would have to have some pretty high load to require > 2 controllers. Not if the drives used have only very small caches. Then you may have one drive's buffer overflow before the other one disconnects for the first time ... (The low end SCSI drives now come with only 128KB of static RAM, some 30% of which are used by the drive's firmware and are not available for data caching and read ahead. I just don't understand why Quantum bothered to support Tagged Command Queues on such a drive (the Fireball TM), with some 90KB of RAM to hold data recently read, to be written and possibly read-ahead ... Regards, STefan