From owner-freebsd-arch@FreeBSD.ORG  Mon Sep 13 19:35:54 2004
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To: Sam <sah@softcardsystems.com>
From: "Poul-Henning Kamp" <phk@phk.freebsd.dk>
In-Reply-To: Your message of "Mon, 13 Sep 2004 15:12:17 CDT."
             <Pine.LNX.4.60.0409131505220.6275@athena> 
Date: Mon, 13 Sep 2004 21:35:52 +0200
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cc: freebsd-arch@freebsd.org
Subject: Re: 4.x device failure? 
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In message <Pine.LNX.4.60.0409131505220.6275@athena>, Sam writes:
>Ah.  Well that answers it.  I'll fail unloading of the
>module if devices are open.
>
>This leads to a curiosity as to how the RAID
>failover modules work at all.  I guess if you abstract
>the real disk(s) under a logical disk you can change
>the bottom layer without affecting the top.  I'll have
>to look at that code a little closer.

You should really start to study GEOM in 5.x which gives a nice
clean framework for all this sort of stuff.

You can start here for instance:

	http://phk.freebsd.dk/pubs/bsdcan-04.slides.geomtut.pdf

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.