Date: Sun, 05 Dec 2004 09:32:17 -0500 From: "Danny J. Zerkel" <dzerkel@columbus.rr.com> To: freebsd-current@freebsd.org Subject: Observations about geom mirror and slices Message-ID: <41B31BF1.50909@columbus.rr.com>
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Just a note about geom mirror and slices. I don't know how many people have run into this yet, but a warning may be in order in the man pages. When I first started experimenting with mirroring on my system, I naively thought I could just mirror any disk partition. Turns out this can be very bad. The problem is that if you mirror a partition that extends all the way to the end of the slice, then geom mirror will think that the mirror part is the entire slice. This is because geom mirror uses the last block for status information. When geom starts tasting the disks, geom mirror sees the last block of the whole slice before it sees the individual partitions. To avoid this, none of the partitions, except c, should include the last block of the slice. Danny J. Zerkel dzerkel@columbus.rr.com
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