Date: Mon, 9 Mar 1998 09:45:19 +0100 From: lada@ws2301.gud.siemens.at (marino.ladavac@siemens.at) To: lada@ws2301.gud.siemens.co.at, shimon@simon-shapiro.org Cc: hackers@FreeBSD.ORG, julian@whistle.com, wilko@yedi.iaf.nl, dmlb@ragnet.demon.co.uk Subject: Re: SCSI Bus redundancy... Message-ID: <199803090845.JAA02668@ws6423.gud.siemens.at>
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> > Consifer a small ISP with, say 5,000 accounts which loses power during ruch > hour. Can you count the number of support calls? > Consider a web server with 2,000 virtual servers. Many used for OLTP, thus > directly generating revenue. If I had my business run on such a server, I > sure would demand it is imunne to power glitches. OLTP does not exists in Austria (i.e. not over Internet). The secure browsers are not available (see ITAR). The other issue is that the power availability seems much better here than in the USA--in the last 5 years I have had no power failures outside one planned (and known two months in advance). This, of course has a bearing on the measures taken to live through the failures, at least for ISP's. > Wrong again. Diesel generators have a 15-180 seconds switch over time. > You use the diesels to feed the battery chargers. The battery packs are > impressive. If you are in the Portland Oregon area, call me and I'll take > you to a small switching center. Fascinating to see. It really depends upon the Diesel backup employed. The hospital grade backup I was describing really kicks in within a few seconds (I seem to recollect that 5 second is a maximum limit). They might be an overkill for the telco people, though (hospital grade power backup deployed around here commonly consists of an 3-phase AC motor, 3-phase AC generator, a Diesel motor and sometimes a smallish DC motor all on the same axle. Usually only the OP's and intensive care are backed up this way, and they never receive the outside power--the power comes always from the generator, and in the case that the outside power fails the Diesel gets immediately injected with fuel--NB it spins at all times--and takes over. The DC motor is intended to help in the possible gap before the Diesel is capable of rated power--afterwards it is used to charge batteries. Now, that is impressive :) A smallish ISP will hardly be able to afford it, nor it seems to be necessary around here. /Marino To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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