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To: Nate Lawson <nate@root.org>
From: "Poul-Henning Kamp" <phk@phk.freebsd.dk>
In-Reply-To: Your message of "Wed, 18 Jun 2003 12:53:52 PDT."
             <20030618125009.K56972@root.org> 
Date: Wed, 18 Jun 2003 21:58:40 +0200
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Subject: Re: cvs commit: src/sys/geom geom_fox.c src/sys/modules/geom
	Makefile src/sys/modules/geom/geom_fox Makefile src/sys/conf NOTES
	files options 
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In message <20030618125009.K56972@root.org>, Nate Lawson writes:
>On Wed, 18 Jun 2003, Poul-Henning Kamp wrote:
>>   Add "GEOM_FOX", a class which detects and selects between multiple
>>   redundant paths to the same device.
>>
>>   This class reacts to a label in the first sector of the device,
>>   which is created the following way:
>>
>>           #    "0123456789abcdef012345..."
>>           #    "<----magic-----><-id-...>
>>           echo "GEOM::FOX       someid" | dd of=/dev/da0 conv=sync
>
>This looks interesting.  Have you shown this to gordon@ who is adding
>something similar to FFS?  It might be good to have a generalized config
>tool.
>
>Won't the location you've chosen interfere with an MBR on i386 drives?
>Is it possible to pick another space (i.e. FFS label, {bsd,sun}label
>fields, GPT)?

No, the FOX method strips off that sector so you will not see it in
the topside device.

>You're right in that it will be a while before disk devices handle
>multipathing themselves.  It would be great if you could help with making
>device_t support this kind of operation.

No way Jose!  I have enough on my plate without adding newbus to the mix.

-- 
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.