[RndTbl] "un-RAIDing" a Linux P2V

[Trevor Cordes]

On 2015-11-30 Wyatt Zacharias wrote:
> --force-lvm-probe and --omit-raid-modules and it still loads dm-raid
> on boot.

dm-raid??  Not md-raid?  What sort of RAID was on this old box?  Can
you still boot the old physical box itself?  What does cat /proc/mdstat
say?  Is there a mdadm.conf?  Or was this back in the raidtools days?

Adam is right, we need a fdisk -l /dev/sdX from the original box for
each drive, too.  If it's 0xFD then changing that might help.

> So how do I get the system to completely forget about RAID, and boot
> off the new virtual disk? Is there a RAID config somewhere that I'm
> missing?

I assume you mean this box was RAID1, right?  Except the partition type
there's not much that stops you using a single RAID1 disk as just a
normal disk.  Adam's right, you don't need to try to get rid of all
md/dm references in the initrd.

You could also try mdadm --zero-superblock option (see manpage).  That
plus getting rid of 0xFD means that single disk is for sure now just a
single disk.  The ancient box might not have that option for mdadm, but
booting of a SRC (or similar) boot cd will let you do it.  DON'T DO
THIS ON THE ORIGINAL BOX unless you have some good full-disk backups.

Oh ya, send us a cat /etc/fstab.  It's probably set to link root to the
md/dm device or label or UUID.  You'll need to change that to a single
disk, UUID is easiest, use blkid to get it.

Oh ya #2, you also need to check your grub (probably grub1?) and what
that says your root is, and change that just like you do for fstab.
You'll need to reinstall grub on the MBR after that too.  I forget how
to do that in grub1!  Probably just grub-install /dev/sdX.

Too bad the ancient RHEL5 doesn't have dracut (right?) and its debug
shell.  Quite handy (if crappy) for these situations.  I've spent WAY
too many hours fighting with this kind of stuff, and learned waaay more
than I wanted to know, but I'm usually going the opposite way, from
non-RAID -> RAID.

If you get stuck and can get me a root ssh into the box (or rescue boot)
I can probably solve your problem in ten minutes! :-)  I also consult,
and can come onsite for a modest fee, though you already knew
that!  :-) ;-)