Message-ID: <46E2D38A.6070607@commandprompt.com>
Date: Sat, 08 Sep 2007 09:53:30 -0700
From: "Joshua D. Drake" <jd@commandprompt.com>
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To: Stefan Kaltenbrunner <stefan@kaltenbrunner.cc>
CC: Gregory Stark <stark@enterprisedb.com>,
	Simon Riggs <simon@2ndquadrant.com>,
	Bernd Helmle <mailings@oopsware.de>, mfatticcioni@mbigroup.it,
	pgsql-performance@postgresql.org
Subject: Re: DRBD and Postgres: how to improve the perfomance?
References: <2C070D1C3970467FF64F6B6A@imhotep.credativ.de>
	<1189232904.4281.19.camel@ebony.site>
	<87k5r1zd52.fsf@oxford.xeocode.com>
	<46E2CAAF.50205@commandprompt.com>
	<46E2CEF3.1030908@kaltenbrunner.cc>
In-Reply-To: <46E2CEF3.1030908@kaltenbrunner.cc>
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Stefan Kaltenbrunner wrote:
> Joshua D. Drake wrote:
>> Gregory Stark wrote:
>>> "Simon Riggs" <simon@2ndquadrant.com> writes:
>>>> You're right, but the distinction is a small one. What are the chances
>>>> of losing two independent servers within a few milliseconds of each
>>>> other? 
>>> If they're on the same power bus?
>> That chance is minuscule or at least should be. Of course we are
>> assuming some level of conditioned power that is independent of the
>> power bus, e.g; a UPS.
> 
> how is that making it different in practise ? - if both are on the same
> UPS they are affectively on the same power bus ...

Well I was thinking the bus that is in the wall. I would assume that
people were smart enough to have independent UPS systems for each server.

city power->line conditioning generator->panel->plug->UPS->server

wash, rinse repeat.

> If the UPS fails (or the generator is not kicking in which happens way
> more often than people would believe) they could still fail at the very
> same time ....

Sincerely,

Joshua D. Drake


> 
> 
> Stefan
> 
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