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Date: Mon, 26 Nov 2001 11:11:05 +1300
From: Chris Wedgwood <cw@f00f.org>
To: "Kevin P. Fleming" <kevin@labsysgrp.com>
Cc: Mark Hahn <hahn@physics.mcmaster.ca>, linux-kernel@vger.kernel.org
Subject: Re: Disk hardware caching, performance, and journalling
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On Sun, Nov 25, 2001 at 02:45:57PM -0700, Kevin P. Fleming wrote:

    I think if you have a large mail server and zero power protection,
    you've got much larger problems to worry about than write-behind
    caching on your disk drives... my servers have never (in my
    memory) experienced a catastrophic power failure, because they're
    too easy to avoid.

In the specific case of email; you want to make certain guarantees,
and having data written to non-volatile storage is one of them.

As for power-failures, given enough time and enough hardware you will
get them, even if your machines are dual or triple powered of diverse
UPSs or -48V powered; it still is possible and _will eventually
happen_ that something further down the line like the motherboard will
fry or whatever.

People who assume that a small-window is small enough and decide that
is 'good enough' are dangerous :)



   --cw
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