[NCLUG] Restore Help?

Bob Proulx bob at proulx.com
Mon Dec 26 10:44:38 MST 2005

Rich Young wrote:
> My home machine (KRUD FC3) recently suffered a mobo failure.  I rebuilt
> with a new processor and mobo, and of course the old Linux install on
> the hard drive won't boot because of the hardware change.

That seems really strange to me.  I often move hard disks around from
computer to computer.  The hardware is often different.  But I
generally expect the machine to boot using hard drive from the other

There are exceptions to this.  At work we use some exotic disk driver
controllers such as the Fusion MPT SCSI and things like that.  If the
driver is not available at boot time such as being saved into the
initrd (initial ram disk) then it won't be able to mount the file
system.  The error is generally "can't open /dev/console".  This is a
cascade failure after not being able to mount the root filesystem.

What is the nature of the failure that you are seeing?

> So I'm a little stuck - should I be using a rescue disc on the original
> installation/original drive, or... what, exactly?

Try booting a live cdrom system such as Knoppix.  Recent systems
should have all of the drivers you need such as SATA, LVM and USB
drivers.  From the Knoppix system mount both your old system disk and
your USB drive.  That should allow you to copy the contents of /home
from your old system to the USB device and recover it.  It should also
dhcp onto a network and you could copy the data off to a network
location.  Onto the network is typically what I have done in the
past.  Then with your data backed up you should be able to reinstall.

Also you should be able to chroot into your hard drive system and
reinstall your kernel.  If the problem is that the initrd needs to be
updated for your new hardware then installing a new kernel should
build a new one for your current hardware.  That should get you back
to booting your original system without need to reinstall it.

[Hint: With older versions of Knoppix that use the ide-scsi and
linux-2.4 kernels you need to boot with the atapicd (IIRC) code to
turn that off to allow you to update the MBR while chroot'd into your
old system.]

When I have had boot problems in the past it has also been possible to
boot live systems that use grub as a boot loader onto the hard drive
system.  I have usually used the DFS live cd for that but any system
that boots grub from the cdrom is useful for this.  If you need hints
on manually telling grub to boot a system off of the hard drive ask

> I've learned already that in the future, /home will be a separate
> partition so that I can preserve it and reinstall over everything else,
> if it comes to that.  I also need to cron my dump of /home to the spare
> drive in the USB drive enclosure, so I'm not caught without a backup
> again.

Yes, those are all good things.  But after you learn how to recover
data from your current system you will then know how to do that in the
future and really having everything on a separate filesystem will then
be less important.

Good luck!

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