Date: Wed, 25 Feb 1998 19:33:12 +0100 (MET) From: Wilko Bulte <wilko@yedi.iaf.nl> To: scsi@FreeBSD.ORG Cc: tom@sdf.com, blkirk@float.eli.net, hackers@FreeBSD.ORG, scsi@FreeBSD.ORG Subject: Re: SCSI Bus redundancy... Message-ID: <199802251833.TAA01362@yedi.iaf.nl> In-Reply-To: <199802251356.FAA18645@silvia.HIP.Berkeley.EDU> from Satoshi Asami at "Feb 25, 98 05:56:01 am"
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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-hackers" in the body of the message
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