Need help switching between two FreeBSD boot drives
Darren David
darren at 3x3x3.org
Thu Jan 5 20:18:11 PST 2006
hi all-
i've got one i've been tearing my hair out over here, and even after
finding some information out there, i'm still totally lost. this may
take a while to explain, so please bear with me.
I've got 2 80GB SATA drives in my FreeBSD machine, which are mapped as
/dev/ad4 and /dev/ad6. I've got 5_STABLE installed on 1 drive, and my
plan is to get a working install of 6_STABLE on the other drive, so i
can take my time to work out the kinks with the upgrade on the 2nd drive
(it hasn't been straighforward) and be able to switch back to my working
5_STABLE machine as needed. That's the plan, anyway.
So I followed the general instructions here:
http://www.freebsd.org/doc/en_US.ISO8859-1/books/faq/book.html#NEW-HUGE-DISK
to clone drive 1 over to drive 2. very cool, no problems, i can pick
either drive in the bootloader and boot up there. so all is well and
good until i boot into drive 2 and start the upgrade process. I realize
the /dev/ad4 and /dev/ad6 are not exactly fixed. It seems almost
arbitrary which drive ends up mapped as /dev/ad6 and /dev/ad4, and this
caused me to nearly munge all of the data on the working 5_STABLE
install before i caught myself. If i boot into drive 1 at boot time,
everything ends up being mounted at /dev/ad6. If i mount into drive 2 at
boot time, the same thing happens. Mind you, i /did/ check /etc/fstab to
ensure that all was well, but i ended up with a weird situation where,
say, / would be /dev/ad4s1a and all of the other mountpoints were at
/dev/ad6*. ugh. confusing!
I found this page, which explains the problem /somewhat/:
http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/install-steps.html
but to be completely honest, the concept didn't stick. What i need help
with, since these drives are exactly the same size and make, is how i
can do the following:
1) determine the relationship between Drive 1/Drive 2 and ad4/ad6
2) determine exactly which physical drive i am working on at any given
time, since the /dev node mappings seem to be malleable
3) enable an environment where i can safely and surely boot into either
drive and know for a fact that the right partitions are mounted ( all of
the data on all of the partitions aside from / is mirrored, so it's
practically impossible to tell which drive is which )
4) (bonus points) My bootloader shows the following on boot:
F1: FreeBSD
F2: FreeBSD
F5: Drive 1
a) I've only got 1 FreeBSD install on this drive, so what is F2? It just
beeps at me when i try it
b) I assume that "F5: Drive 1" means that the drive i'm staring at the
options for is Drive 2, adn that selecting F5 will toggle to Drive 1?
Just clarifying!
i hope this is an easy one to solve. i look forward to any and all help!
thanks in advance,
darren david
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