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Date:      Thu, 20 Sep 2001 23:13:04 -0400
From:      "Brandon S. Allbery KF8NH" <allbery@ece.cmu.edu>
To:        "David W. Chapman Jr." <dwcjr@inethouston.net>, "Daniel O'Connor" <doconnor@gsoft.com.au>
Cc:        Nuno Teixeira <nuno.mailinglists@pt-quorum.com>, freebsd-stable@FreeBSD.ORG
Subject:   Re: hw.ata.wc && hw.ata.tags && softupdates short question
Message-ID:  <107060000.1001041983@vpn58.ece.cmu.edu>
In-Reply-To: <20010920215107.B78811@leviathan.inethouston.net>
References:  <20010920211704.C7820@gateway.bogus> <XFMail.20010921121832.doconnor@gsoft.com.au> <20010920215107.B78811@leviathan.inethouston.net>

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On Thursday, September 20, 2001 21:51:07 -0500, "David W. Chapman Jr." 
<dwcjr@inethouston.net> wrote:
+-----
| > Well you can but if you lose power you WILL lose data.
| >
| Doesn't harware write cache usually write itself to disk before power
| outage or even after?
+--->8

My understanding is that modern drives typically have such large caches 
that they can't actually guarantee flushing the entire cache to disk on 
power failure before the capacitor(s) that store power for the purpose 
discharge.  You might be lucky if the cache is relatively empty, or you 
might lose.

-- 
brandon s. allbery  [os/2][linux][solaris][freebsd]   allbery@kf8nh.apk.net
system administrator   [JAPH][WAY too many hats]        allbery@ece.cmu.edu
electrical and computer engineering                                   KF8NH
carnegie mellon university     [linux: proof of the million monkeys theory]


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