[GLLUG] Help with Centos: old disks in new PC

[damion.yates at gmail.com]

On Sat, 9 Nov 2013, Alain Williams wrote:

> On Sat, Nov 09, 2013 at 11:53:28AM +0000, Sharon Kimble wrote:
> 
> > Does a live disk, any variety of linux, work? If that works, then I
> > would suggest dodgy drives. I.e. retrieve as much info as possible
> > and try with new drives. And then once its working, restore from
> > backup. If the old machine was 'cooked' then I would surmise that
> > the old hard drives would have some element of damage too and would
> > be better off being replaced. 
> 
> Yes, the old hard disks work nicely. As I mentioned: I am able to
> mount them, chroot & run commands. Ihave run a liveCD

If you can get this far then it should be possible to use the livecd as
minimally as possible, using it as the initial boot.

Copy over the initrd or livecd's /lib/modules/x.xx.xx modules to the
root disk, then get it to as little past mounting its initramfs root and
see if you can pivit_root or possibly it'd work with just chroot, and
get the old system's init to startup the system from there, it should be
able to start everything else (system daemons and end with the login
gettys or X11) as normal unless you have complicated things like raid to
configure or esoteric hardware that the livecd's modules directory lacks
kernel module drivers for.

If this works, (or alternatively but still with the modules directory
copy) tell the livecd at its boot menu (syslinux/isolinux?) to have
root=/dev/<realrootdisk>.

Booting with a modern kernel+mods is more likely to get past any modern
hardware/HAL problems compared the one you suspect is panicking that
comes from the system disk.  Some stuff might not work regarding
hotplug/raid/esoteric hardware and depending on how old the OS was it
/may/ have some binary incompatibility communicating with the kernel
system calls (SYSENTER vs int80, regparams vs stack, however you said
chroot executing works, so actually this should not be an issue).

This bypasses your suspected kernel issues assuming it's crashing before
it even tries to start init.

If either technique does work and brings up the system to a state where
you're happy enough, you can copy the kernel to disk and reconfigure
grub.  This technique would be similar to how chrubuntu operates, in
that the kernel and its modules are not related to what the OS
installed/knows about.


 - Damion