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Date: Wed, 27 Apr 2011 15:52:16 +0200
From: Miroslav Lachman <000.fbsd@quip.cz>
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To: Daniel Kalchev <daniel@digsys.bg>
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Cc: freebsd-fs@freebsd.org
Subject: Re: Why not just name the cam-ata devices the same as the old,
	names?
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Daniel Kalchev wrote:

[...]

> What should be done, ideally before the 9.0 release is to find some sane
> resolution method of what happens when you happen to have two (for
> example) 'root' UFS labels during boot/mount time.

...and that's the problem with labels in case of gmirror.
When you create gm0 of ada0 and ada1, then sometime in the future ada0 
timedout and is dropped by gmirror, on next reboot you will have same 
partitions available on device /dev/ada0 and /dev/mirror/gm0 so there 
will be two devices promoting same labels! I don't know the order of 
tasting devices, but there is a chance that system will boot (mount root 
by label) from broken ada0 instead of gm0.
That's why I am staying away from labels on gmirrored disk. (I am using 
labels on USB flash disks or USB external drives)

Miroslav Lachman