From owner-freebsd-questions@FreeBSD.ORG Tue Dec 2 08:22:01 2014 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 6B2152C1 for ; Tue, 2 Dec 2014 08:22:01 +0000 (UTC) Received: from agora.rdrop.com (agora.rdrop.com [IPv6:2607:f678:1010::34]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 24144355 for ; Tue, 2 Dec 2014 08:22:01 +0000 (UTC) Received: from agora.rdrop.com (66@localhost [127.0.0.1]) by agora.rdrop.com (8.13.1/8.12.7) with ESMTP id sB28Lt4j094113 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NOT); Tue, 2 Dec 2014 00:21:55 -0800 (PST) (envelope-from perryh@pluto.rain.com) Received: (from uucp@localhost) by agora.rdrop.com (8.13.1/8.14.2/Submit) with UUCP id sB28LtqS094112; Tue, 2 Dec 2014 00:21:55 -0800 (PST) (envelope-from perryh@pluto.rain.com) Received: from fbsd81 by pluto.rain.com (4.1/SMI-4.1-pluto-M2060407) id AA09137; Tue, 2 Dec 14 00:13:43 PST Date: Tue, 02 Dec 2014 00:13:40 -0800 From: perryh@pluto.rain.com (Perry Hutchison) To: aimass@yabarana.com Subject: Re: OT: UPS for FreeBSD Message-Id: <547d74b4.qPmD4NU27Cup8Ccm%perryh@pluto.rain.com> References: <54777AB1.9010800@bluerosetech.com> <54779629.302@bluerosetech.com> <5478BD4F.7020306@yahoo.com> <5478BEE6.30308@bluerosetech.com> <5478CC08.9090307@yahoo.com> <20141128204722.561f948e@archlinux> <5478F16A.80605@yahoo.com> <54791d3a.w/pI0kak03d+3nKC%perryh@pluto.rain.com> <20141129113405.3d1bd1d6@X220.alogt.com> <54798883.saa13h6lE6rPwZCf%perryh@pluto.rain.com> <20141130212746.6d5eaf1f@X220.alogt.com> <547bd5bd.dKE49fHIj28ERZyT%perryh@pluto.rain.com> <20141201140037.584faf7e@X220.alogt.com> In-Reply-To: User-Agent: nail 11.25 7/29/05 Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: erichsfreebsdlist@alogt.com, kudzu@tenebras.com, freebsd-questions@freebsd.org X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 02 Dec 2014 08:22:01 -0000 Alejandro Imass wrote: > ... at high power you would still need to employ high voltage to > decrease loss in the distribution, or you would need to employ > ridiculously large conductor bars to be able to distribute > low-voltage DC even in the most modest data center ... Oh, for Pete's sake! What part of "integrate a UPS with the PSU" (http://lists.freebsd.org/pipermail/freebsd-questions/2014-November/262603.html) is so hard to understand? I'm proposing that the individual PSUs be designed in such a way that a battery or two can be connected into each PSU, between the rectifier and the regulator. The cables between the PSU and its batteries would be maybe a foot long (if the batteries are mounted adjacent to the server, say in the next rack slot above or below) -- or up to a couple of meters long if all the batteries were housed in the bottom part of the rack with all the servers above -- and the conductors would not need to be much (if any) heavier than those connecting the regulator outputs to the circuit boards. Of course, if one insists on serving a whole data center (or even just one full server rack) from a _single_ UPS, that UPS is going to be a massive piece of equipment and the power distribution to its loads is going to require infrastructure commensurate with the amount of power involved. (It's also not all that reliable an arrangement, since the UPS becomes a single point of failure capable of taking down many systems.)