From owner-freebsd-stable Tue Jul 24 22:52:11 2001 Delivered-To: freebsd-stable@freebsd.org Received: from smtp.wanadoo.nl (smtp0.wanadoo.nl [194.134.193.6]) by hub.freebsd.org (Postfix) with ESMTP id 0991637B401; Tue, 24 Jul 2001 22:52:07 -0700 (PDT) (envelope-from steveo@eircom.net) Received: from ams-gw.sohara.org (p1221.vcu.wanadoo.nl [194.134.203.202]) by smtp.wanadoo.nl (8.11.2/8.11.2) with SMTP id f6P5q2a17508; Wed, 25 Jul 2001 07:52:02 +0200 (MET DST) Date: Wed, 25 Jul 2001 07:51:58 +0200 From: "Steve O'Hara-Smith" To: Wilko Bulte Cc: jkh@FreeBSD.ORG, mike@adept.org, jandrese@mitre.org, geniusj@bluenugget.net, mike@sentex.net, sucho2@quasar.phys.vt.edu, mwm@mired.org, freebsd-stable@FreeBSD.ORG Subject: Re: Regarding hw.ata.wc="1"...... Message-Id: <20010725075158.0e5df923.steveo@eircom.net> In-Reply-To: <20010724220400.A1558@freebie.xs4all.nl> References: <3B5D94E7.4680ACEF@mitre.org> <20010724093512W.jkh@freebsd.org> <20010724204131.355a3ae6.steveo@eircom.net> <20010724220400.A1558@freebie.xs4all.nl> X-Mailer: Sylpheed version 0.4.99cvs3 (GTK+ 1.2.10; i386-unknown-freebsdelf4.3) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-freebsd-stable@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG On Tue, 24 Jul 2001 22:04:00 +0200 Wilko Bulte wrote: WB> > favour of a complete spare system and use a software mirror (or load WB> > duplication) to keep it available for a hot swap. One benefit of this approach WB> > is that the hardware is on *much* shorter lead times this way because it's all WB> > off the shelf and alternatives are feasible. WB> WB> But lots more downtime if you are unlucky. Like you said, it all depends on You only get downtime if you lose *both* systems in the time it takes to fix a breakage. Higher levels of redundancy are of course trivial. WB> > There's more than one way to skin a cat. WB> WB> You should not talk about skinning cats in Jordan's presence. Ooops, sorry Jordan. ... Two replies in one this is OT after all ... MM> one system crashing. What's in the intersection are things that shut MM> down the power to the active machine but not the hot spare, which are MM> normally pretty rare. Parallel power sources will make them more MM> common, but that's a more expensive proposition than just keeping a Two small UPSs is not a major expense, and will ensure enough PSU reliability that you don't lose *both* machines without at least one completing a shutdown unless you get multiple UPS failures. If there are two phases in the building use them to reduce the probability of simultaneous mains failure too. -- Directable Mirrors - A Better Way To Focus The Sun http://www.best.com/~sohara To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message