[CentOS] SOLVED: hard disk move to another server
dmcleod at foranyauto.com
Mon Apr 9 19:02:54 UTC 2007
Thanks for posting this.
I wanted to do this once or twice in the past, but never bothered to figure
I will be trying it soon...
I have a Mondo Backup of a server that I want to move to less powerful
hardware, and hopefully this will do the trick.
From: centos-bounces at centos.org [mailto:centos-bounces at centos.org] On Behalf
Sent: Monday, April 09, 2007 11:22 AM
To: CentOS mailing list
Subject: Re: [CentOS] SOLVED: hard disk move to another server
>You can at least try to prepare a new initrd (name it differently and
>create a different entry in grub.conf) with mkinitrd.
>mkinitrd has a nice feature called --with=module so you can try to
>mkinitrd --with=sata_via to include this module even if not 'already'
>specified in /etc/modprobe.conf (don't forget also to change this after
>the machine has correctly booted : 'alias scsi_hostadapter=') I've
>never tested such hdd migration but it should work ...
Sorry for the very late answer.
You are right, this did the trick. However, there was a thing to add to make
it work, we need to mount the /proc filesystem on the destination root
directory for the mkinitrd to work properly. Else, thank you very much for
the help you provided!
The quick fix is to simply copy the /boot/initrd-xx.img file from a working
installated drive on the destination server to the old drive partition, and
it will work (you must update the grub entry of course).
However, if you don't have such a working hard drive, you will need to
recompile this initrd file. Therefore I post the complete procedure below to
move a hard disk drive with a working CentOS 4 system from one server to
another one, not having the same SATA chips, or from a PATA to an SATA or
If you don't do this, then you might receive this kind of error:
Uncompressing Linux... Ok, booting the kernel.
Red Hat nash version 18.104.22.168 starting
mount: error 6 mounting ext3
mount: error 2 mounting none
switchroot: mount failed: 22
Kernel panic - not syncing: Attempted to kill init!
Here is my procedure for those who would need it:
1. To recreate the initrd file, we will do it by booting from a successful
boot partition on the destination server, like the CentOS live CD for
example, or any other hard drive a hard drive which has been installed with
the CentOS installer on the destination server.
We will mount the destination (failing) boot filesystem to /mnt/boot, and
also its associated destination root filesystem, with these commands:
mount /dev/sda1 /mnt/boot
mount /dev/sda3 /mnt/root
2. We must now change the root directory so that we can have access to the
latest kernel sources which is always in /lib/modules. However, we must
first create the /proc filesystem on the chrooted partition, else the
compilation won't work properly:
mount -t proc none /mnt/root/proc
3. Then, we can chroot to that partition like this:
4. We then rebuild an initrd file by typing the following:
mkinitrd --with=sata_via /initrd-new.img 2.6.9-42.0.10.EL
To know the proper kernel version to use (last number of the command line),
you need to use an existing directory listed in the /lib/modules directory.
Normally you should take the last one.
the --with=sata_via is to force specifying the right hard disk module to
use, but it can normally be omitted. Else make sure that you specify the
proper driver for your motherboard SATA hardware chip.
We do not create the initrd file in the boot directory, because we can
sometimes not access it at this time (especially with md partitions), but we
will simply copy the resulting file to the proper destination afterwards.
If you receive an error message saying 'unable to stat /dev/md2: 2', just
forget about it, the resulting file should still be there.
5. Make sure that the /etc/modprobe.conf file contains the driver you have
added to this line:
alias scsi_hostadapter sata_via
6. Now, let's come out of the chroot:
7. Then, copy the resulting file to the proper destination:
cp /mnt/root/initrd-new.img /boot
8. Finally, we need to add the entry in the /boot/grub/grub.conf file, by
keeping the last kernel file, but changing the initrd file to the new one.
9. Make sure that the following files have been properly changed accordingly
to your new server setup:
All should be done now. You can reboot and try the result...
Thanks to all the others who also helped me with this problem.
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