From owner-freebsd-scsi Wed Feb 25 11:03:59 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id LAA20150 for freebsd-scsi-outgoing; Wed, 25 Feb 1998 11:03:59 -0800 (PST) (envelope-from owner-freebsd-scsi@FreeBSD.ORG) Received: from uni4nn.gn.iaf.nl (osmium.gn.iaf.nl [193.67.144.12]) by hub.freebsd.org (8.8.8/8.8.8) with SMTP id LAA20028; Wed, 25 Feb 1998 11:03:26 -0800 (PST) (envelope-from wilko@yedi.iaf.nl) Received: by uni4nn.gn.iaf.nl with UUCP id AA14658 (5.67b/IDA-1.5); Wed, 25 Feb 1998 20:03:22 +0100 Received: (from wilko@localhost) by yedi.iaf.nl (8.8.7/8.6.12) id TAA01362; Wed, 25 Feb 1998 19:33:12 +0100 (MET) From: Wilko Bulte Message-Id: <199802251833.TAA01362@yedi.iaf.nl> Subject: Re: SCSI Bus redundancy... In-Reply-To: <199802251356.FAA18645@silvia.HIP.Berkeley.EDU> from Satoshi Asami at "Feb 25, 98 05:56:01 am" To: scsi@FreeBSD.ORG Date: Wed, 25 Feb 1998 19:33:12 +0100 (MET) Cc: tom@sdf.com, blkirk@float.eli.net, hackers@FreeBSD.ORG, scsi@FreeBSD.ORG X-Organisation: Private FreeBSD site - Arnhem, The Netherlands X-Pgp-Info: PGP public key at 'finger wilko@freefall.freebsd.org' X-Mailer: ELM [version 2.4ME+ PL32 (25)] Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-freebsd-scsi@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org As Satoshi Asami wrote... > (Redirected to -scsi) > > * SCSI adapter rarely fail. > > By the way, we're more concerned about network switch/cable/PC/power > supply failures, rather than adapters. There are so many things that Use a hot-swap disk chassis with redundant power supplies. Hook those up to a *good* UPS. Regularly check you lead-acid creeps (the UPS batteries). > can take down a machine, and if it's the single connection from the > disk to the network, it's not good. Multiple adapters on a single disk do not buy you much either. If adapter A decides to commit suicide and locks up the bus real good adapter B is still stuck. You want some kind of a bus isolator thingy. The company I work for (DEC) is releasing what is called SCSI hubs. These are multiport devices that can 'star couple' (for lack of a better terminology) multiple scsi buses, with each bus being electrically seperated. The larger hubs have a round robin arbitration builtin that makes sure that the host with ID 7 will not monopolise the bus to the device. All of this is based on a chip jointly developed by Digital and Symbios See www.symbios.com for more info. Wilko _ ______________________________________________________________________ | / o / / _ Bulte email: wilko @ yedi.iaf.nl http://www.tcja.nl/~wilko |/|/ / / /( (_) Arnhem, The Netherlands - Do, or do not. There is no 'try' --------------- Support your local daemons: run [Free,Net,Open]BSD Unix -- To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message