[gentoo-user] Boot disk "renames" /dev/md6 to /dev/md127.

[Alan Mackenzie]

Hi, Gentoo!

I've been in the wars.

It's so long since I've updated my system, many months, mainly because I
got totally confused with changes to portage, and the mess that resulted
from gnome 3 becoming stabilised, and hence my XFCE support being
drastically undermined.  However, it's still a working system, and I'm
loathe to go messing around in it, considering how high the risk is of
ending up with a non-working system.

So, why not a new installation, in parallel with my existing one?
Sounds like a good idea.  So, I read up the new Gentoo handbook in the
Gentoo wiki, downloaded the latest installation iso, and burnt it onto a
re-recordable CD.

I booted into this CD image, giving the kernel the "please enable LVM2"
parameter, and played around with this, mounting various partitions, and
generally checking I had access to all of them in this system.
Everything seemed fine.

Then I tried to boot back into my normal system.  Kernel panic!  The
root file system, /dev/md6, was missing.  (/dev/md6 is a software raid
partition (RAID-1) built on /dev/sda6 and /dev/sdb6.)  Luckily, the
kernel messages detailing the RAID assembly were still visible.  It
appeared that the kernel had built /dev/md127 instead of /dev/md6.

Several hours of lost sleep later, I managed to boot into an older
kernel with a different root file system, and with the help of chroot
was able, eventually, to access my /etc/lilo.conf, replace md6 by md127,
re-run lilo, and boot "normally".

So, what was it that chewed up my RAID configuration so badly that
/dev/md6 got renamed to /dev/md127?  Can I change it back to /dev/md6,
somehow?  Do I need to bother?  How can I ever trust a Gentoo
installation CD again?

In fact, do I really need an installation CD for a new installation?
Would I perhaps be better creating new partions then downloading a stage
3 from my working system?

-- 
Alan Mackenzie (Nuremberg, Germany).