[CentOS] Using CentOS Live CD to recover trashed RHEL system

Fri Jun 25 05:43:57 UTC 2010
drew einhorn <drew.einhorn at gmail.com>

On Thu, Jun 24, 2010 at 7:53 PM, Joseph L. Casale <jcasale at activenetwerx.com
> wrote:

> > The part I'm not certain about is the grub voodoo to get the system to
> boot to
> > the lvm with the restored root file system.
> Look at ./etc/lvm/backup/* in your dumped files, it will show you the VG,
> LV and ID. Create your new VG and LV, then edit fstab to reflect or
> recreate it w/
> the same names. Just make sure fstab reflects whats actually in place.

The seems to be something here that I don't get!

I have booted from a cd and am running CentOS,  I'm assuming my active root
file system is some sort of read/write ram disk overlaid on top of the read
only file system from the cd.  At the moment the right terminology to
express this escapes me.

I have the original system disk that is corrupted.  It needs at least two
partitions since the boot loader does not yet understand lvm.  There is a
tiny ext2/3 file system that contains /boot which contains the boot
loader/grub stuff.  I assuming we are talking about "legacy grub" not grub2.
And there is a second partition containing an lvm PV and within that is a LV
containing the root file system.

I do have a level 0 dump of /boot in addition to the level 0 dump of /

I can restore the contents of /boot and / but things will proabably not end
up in the same physical sectors.  Running grub the right way should update
parameter for the boot loader to first tranfer control to the right place in
/boot which then accesses the right filesytem in the right PV/LV

You seem to be saying that all I need to to do is tweak /etc/fstab in the
root file system
in the new pvn/lvm.

Actually as I try to explain my current understanding things are getting

It seems to me that at least one more step is required.   getting a proper
chroot jail environment set up so I can run a grub command to update the
boot sectors on the RHEL5 system disk to transfer control to the right place
in /boot and update /boot so that it can mount the right filesystem on /

I'm still hoping to find complete documentation with an example of how to do

Drew Einhorn

"You can see a lot by just looking."
 --  Yogi Berra
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