CentOS - Jan 2009 - Help with a good recovery plan.. Linux rescue?

Hello All,

I have a machine that crashed. Some part of the motherboard (power 
supply-related) went south.

The motherboard, CPU and memory have been replaced with a much newer 
architecture. The OS and data are intact on two SATA drives that were 
RAID1 with LVM.

I am going to use 'linux rescue' to recover the LVM backup so I can 
mount the RAIDs (there were two) in a new CentOS install, on a third disk.

I have no indication that I could recover the previous CentOS 
(somewhere between CentOS 5.1 and 5.2 on updates).

Can I use 'linux rescue' to fix that OS up to boot it? The kernel 
panics in its current state (because the hardware architecture is so 
strikingly different). What is the methodology of fixing the kernel 
in this circumstance?

Thanks in Advance!
Glenn

On Mon, Jan 19, 2009, Glenn wrote:
>Hello All,
>
>I have a machine that crashed. Some part of the motherboard (power 
>supply-related) went south.
>
>The motherboard, CPU and memory have been replaced with a much newer 
>architecture. The OS and data are intact on two SATA drives that were 
>RAID1 with LVM.
>
>I am going to use 'linux rescue' to recover the LVM backup so I can 
>mount the RAIDs (there were two) in a new CentOS install, on a third disk.
>
>I have no indication that I could recover the previous CentOS 
>(somewhere between CentOS 5.1 and 5.2 on updates).
>
>Can I use 'linux rescue' to fix that OS up to boot it? The kernel 
>panics in its current state (because the hardware architecture is so 
>strikingly different). What is the methodology of fixing the kernel 
>in this circumstance?
I don't know that this will be a major problem if my experience
years ago going from Caldera OpenLinux something-or-other to SuSE
Pro was any example.  The old Caldera system had a multi-disk
LVM RAID which I had moved to a newer system, fully expecting to
lose the data after installing a new Linux OS on the system.

I did a fresh install on the primary HD without touching the
external RAID drives, and, much to my surprise, the new Linux
found the RAID drives, asking if I wanted to mount them.

Bill
-- 
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from too much government. --Thomas Jefferson.

>Can I use 'linux rescue' to fix that OS up to boot it? The kernel 
>panics in its current state (because the hardware architecture is so 
>strikingly different). What is the methodology of fixing the kernel 
>in this circumstance?
You likely don't have block device modules for whatever controller this
new rig has in your initrd.

Deduce that in your rescue environment (look for something obvious), here
are some examples (IDE|SATA|SCSI):

# lspci
00:1f.2 IDE interface: Intel Corporation 82801H (ICH8 Family) 4 port SATA IDE
Controller (rev 02)
00:1f.5 IDE interface: Intel Corporation 82801H (ICH8 Family) 2 port SATA IDE
Controller (rev 02)
03:00.0 SATA controller: JMicron Technologies, Inc. JMicron 20360/20363 AHCI
Controller (rev 03)
03:00.1 IDE interface: JMicron Technologies, Inc. JMicron 20360/20363 AHCI
Controller (rev 03)

Figure out what module supports it. Maybe see where it resides in the
modules/src tree?
# lsmod
ata_piix               22341  4
libata                143997  2 ahci,ata_piix
scsi_mod              134605  3 sg,libata,sd_mod
# locate scsi_mod
/lib/modules/2.6.18-92.1.18.el5/kernel/drivers/scsi/scsi_mod.ko
/usr/src/kernels/linux-2.6.28-rc6/drivers/scsi/scsi_module.c

Obviously scsi_mod is a scsi module (Block Device), and I am using it... 

Then either add them to your modprobe.conf which is read by mkinitrd or use cli
options in your
mkinitrd command.
# cat /etc/modprobe.conf
alias eth0 e100
alias eth1 r8169
alias scsi_hostadapter ata_piix
alias scsi_hostadapter1 ahci

Generate this new initrd (man mkinitrd) and force the kernel you currently have
*on the dead system*,
look in /boot.

Edit grub.conf to use this new initrd, make a new stanza maybe?

Edit your fstab to reflect any changes that might occur as a result, such as
migrating from an IDE
block device to a SCSI one: /dev/had --> /dev/sda etc. unless of course you
are using LVM on the system
disc as well.

I suspect (but you didn't provide much info) that since these very same
discs are in the new machine,
they have a compatible interface which hasn't changed (obviously, they were
SCSI or SATA etc) and your
new rig likely has newer devices which need newer modules maybe like if the
system disc was IDE or SATA
on an old controller?

Could be something else, post back with any progress.

HTH,
jlc