Re: [PLUG] How best to replace old drive with new drive

[JP Vossen <jp@jpsdomain.org>]

> Date: Fri, 19 Oct 2007 12:36:34 -0400
> From: Mike Leone <turgon@mike-leone.com>
> Subject: [PLUG] How best to replace old drive with new drive
>
> So I've got a mail server that has an old HD. And I wanna replace it with a
> larger one, which I happen to have lying about. I know there's any number of
> ways to clone the HD (me, I like Ghost, but I also have DriveImageXML, and I
> suppose I could even do a dd). Anyways, if I were to Ghost to the new drive,
> what would I need to do to make grub run on it? I seem to remember doing
> this before, and getting a new drive with larger partitions, but grub
> wouldn't run.
>
> A pointer or clue, anyone? Something about booting a Knoppix LiveCD, and
> running "grub-install", I believe?

"Simple" answer:
----------------
1) Install the new hard drive in the old machine
2) Boot a LiveCD or into recovery or single user mode
3) partition and format the new drive, then mount it +
4) rsync the data over *
5) chroot into the new drive's root
6) Recreate dirs as needed: mkdir /dev /proc /tmp
7) run "grub-install"
8) Remove old drive and boot into new one

+ MAKE SURE YOU USE THE RIGHT DRIVE!  It you have any question, 
disconnect the good/old drive and install only the new one until you get 
this right.

When I do this, and when I'm using multiple partitions, I'll do 
something like tis.  It's a bit more work but it duplicates the final 
disk's structure, facilitating a later chroot for grub install.
	cd /mnt
	mkdir new
	mount -t ext3 /dev/sda2 /mnt/new
	mkdir new/boot
	mkdir new/home
	mount -t ext3 /dev/sda1 /mnt/new/boot
	mount -t ext3 /dev/sda5 /mnt/new/home

* SAMPLE rsync command, tweak and test as needed:
	rsync -v -a --numeric-ids \
	  --exclude /mnt \
	  --exclude /var/cache/yum/base/headers/* \
	  --exclude /proc \
	  --exclude /dev \
	  --exclude /tmp \
	  --exclude other_stuff_as_needed \
	  /. /mnt/new

Since you are duplicating a disk, --numeric-ids isn't really necessary 
since the passwd files will end up the same.  I only use it out of habit.

Depending on your distro, you might not want to skip /dev.  Anything 
using udev should re-created whatever is needed in /dev at boot (someone 
correct me if I'm wrong).  Anything older *not* using udev won't; in 
that case copy /dev too.



More complicated, multi-machine answer:
---------------------------------------
This is how I've done machine to (virtual) machine disk copies:
	http://communities.vmware.com/thread/22724#281540
	http://communities.vmware.com/thread/22724#281765

You'll see that these instructions are about copying disks into VMware, 
and that I started out overly complicated (I do that a lot).  The 
process "devzero" outlined in #281540 worked for me, with trivial 
additions I noted in #281765.

While I have enlarged ext3 partitions in the past, that makes me nervous 
(yeah, I'm paranoid too).  While my processes have more steps than some 
suggested, I consider it less risky (I'm conservative too).  In your 
case, you obviously omit the VMware parts and just do the disk-to-disk 
parts.

Hope this is useful,
JP
----------------------------|:::======|-------------------------------
JP Vossen, CISSP            |:::======|        jp{at}jpsdomain{dot}org
My Account, My Opinions     |=========|      http://www.jpsdomain.org/
----------------------------|=========|-------------------------------
Microsoft has single-handedly nullified Moore's Law.
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