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Date:      Mon, 21 Jan 2002 00:59:10 -0800
From:      "Crist J . Clark" <cjc@FreeBSD.ORG>
To:        Sir <postroad@mediaone.net>
Cc:        mwm@mired.org, questions@FreeBSD.ORG
Subject:   Re: The tower of Hanoi
Message-ID:  <20020121005910.J66815@blossom.cjclark.org>
In-Reply-To: <3C4B83A4.FA87DB7E@mediaone.net>; from postroad@mediaone.net on Sun, Jan 20, 2002 at 09:57:42PM -0500
References:  <3C4B83A4.FA87DB7E@mediaone.net>

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On Sun, Jan 20, 2002 at 09:57:42PM -0500, Sir wrote:
> I was following a thread  in the freebsd mailing list that you replied
> on.  Seems like you have some experience with "dump". A read of the man
> pages has a realy baffling bit about the tower of hanoi algorithm. It
> says incrementals should be taken on a daily basis 3 2 5 4 7 6 9 8 9
> 9.... It then goes on to say that a weekly should be taken with level
> 1.  Well, there's more than 7 levels there so I'm not sure how it all
> fits together.

It's all just a suggestion. If you were to do the once-a-week thing,
it would work something like,

      S S M T W T F

      1 3 2 5 4 6 9

Rinse, repeat... The motivation for using that type of algorithm is
that you tend to balance the amount of data dumped each day (amount of
dump media consumed) versus how many steps one would need to take to
restore a filesystem.

> It reads like they should be done all in the same day??

No, in the example, we are doing one dump per day.

> I
> was under the impression you shouldn't "dump" a disk unles it's
> umount'd.

Ideally, you would like a static filesystem, but this simply is not
realistic for most sites. dump(8) has no problem dumping a live file
system, but don't fool youself into believing a dump is a "snapshot"
of the filesystem.

> And, for us real newbies, how do you un-dump??

restore(8).
-- 
Crist J. Clark                     |     cjclark@alum.mit.edu
                                   |     cjclark@jhu.edu
http://people.freebsd.org/~cjc/    |     cjc@freebsd.org

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