Proper gmirror install

[Sean C. Farley]

I have been experimenting with installing FreeBSD using only gpart from 
the 8.0-BETA4 DVD.  It has been helping my understanding of GPT vs. MBR. 
Now, I would like to verify the setup[1] I have made and the messages I 
am getting from it.

The basic setup is for both disks:
Slice       Type                    Size
ad0s1       Windows7 system         100MB
ad0s2       Windows7                20GB
gm0s3       FreeBSD (non-swap)      20GB        ad0s3 and ad1s3
ad0s4       FreeBSD (swap)          2GB

I am creating the mirror prior to creating the BSD label.  I also take 
it from this posting[2] that it is the preferred method.

Everything appears correct, however, I am getting these messages:
GEOM: ad0s3: geometry does not match label (255h,63s != 16h,63s).
GEOM: ad0s3: media size does not match label.
GEOM: ad1s3: geometry does not match label (255h,63s != 16h,63s)
GEOM: ad1s3: media size does not match label.

Questions:
1. Is this due to the BSD label being within the mirror and is
    considered safe?
2. Am I correct in my understanding that having the BSD label within the
    mirror takes care of the need to hardcode the provider's name and/or
    subtracting one from the c: partition?
3. Other than not being able to boot directly from those slices
    (untried; maybe not true) as opposed to the mirrored slice, is there
    any other concern doing it this way?
4. gpart allows more than four slices to be created.  Are those primary,
    extended or something else?
5. Any other suggestions?  I plan on putting this example on the wiki
    once it is verified to be correct.

BTW, I must say I like using gpart after getting used to it.  It would 
be nice if it could also handle creating and maintaining a hybrid 
MBR/GPT setup.

Sean
   1. http://people.freebsd.org/~scf/gmirror-install.txt
   2. http://lists.freebsd.org/pipermail/freebsd-current/2009-June/008638.html
-- 
scf at FreeBSD.org