tbku / Imaging-SUSE-Linux-With-tbku.txt
How To Image SUSE Linux Systems Using ``tbku``

This document describes how to use the TundraWare Inc. ``tbku``
utility to "image" or "clone" SUSE Linux systems.

        .. Note::

               Most/Much of this will also be relevant to other Linux
               distributions, though some of the fine points may be

Why Bother Imaging?

Suppose we need to build a new instance of a ``SUSE Linux`` system.
Perhaps we need to replace one that just had a hard drive failure.
Maybe we want to build a new server that is based on our "standard"
system configuration.  In other words, we want to go from "bare
metal" hardware to a fully running *and configured* system as quickly
as possible.

There are a number of commercial and open source solutions to this
problem, but they all have one thing in common: We want to minimize
the amount of manual labor needed to install, configure, and otherwise
customize the final system.  This is especially important in large
data centers where it is impractical to manually (re)install each and
every server, its applications, and its customization information.

"Imaging" or "Cloning" allows us to keep a copy of the entire OS *as
configured* - that means with all its applications and configuration
options set up as desired.  We then load or "Provision" a new hard
drive with this image and *voila'*, "instant" running system.

What Is ``tbku``?

``tbku`` is a shell script that makes it easy to create tarballs of
some of all of your filesystems.  ``tbku`` does not help you with
*restoring* your image, it's just handy for creating the image in the
first place.

If you've never used it before, take a moment to download it and read
the documentation.  You'll find the latest copy at:

There is no fee for using ``tbku`` in any context, personal or
commercial.  However, there are some licensing terms you have to abide
by to use it, so take a moment to read the license in the distribution

        .. Note::

               You don't *have* to use ``tbku`` to create your backup
               image.  The description below should work fine so long
               as you have a backup of all the relevant files that
               preserves all the appropriate file information such as
               ownership and permissions.  ``tbku`` just makes it easy
               to automate the creation of such backups.

The Big Picture

Before diving into the details, it's good to get a sense of the
overall process.  Imaging a system requires the following steps:

    A. Create the master image:

       - Create a baseline system configured as you want it.
       - Take an "image" of it.  (That's where ``tbku`` is helpful.)
       - Save the image somewhere (DVD, USB drive, network drive ...)
         you can get at when you need it to (re)install a system.

    B. Use the master image to (re)provision a machine:

       - Prepare the target hard disk to receive the image.
       - Dump the image onto the hard disk.
       - Adjust the configuration if/as needed for the new hardware.

Creating The Master Image

Unlike other approaches that make an image of *the disk*, ``tbku``
creates an image of *files* on the disk.  This means that your new
target disk does not have to be physically the same as the one on
which the master image (sometimes called a "snapshot") was made.  You
can clone systems back and forth between SCSI, IDE, and SATA.  You can
clone from smaller disks to larger ones or go the other way.

        .. Note::

               The whole point of doing imaging is to avoid having to
               do custom configuration for each new installation.
               However, some configuration changes may be necessary
               when the target hardware is different than the hardware
               on which the master image was created.  This is
               discussed a bit more below in the `Gotchas`_ section.

    Creating The Master Image

       1. Select the machine whose existing SUSE Linux installation
          you want preserved or used as a standard installation image.

       2. Image that system with ``tbku`` using the following


          Notice that we do *not* backup the dynamic kernel-created
          filesystems like ``/dev`` or ``/proc``.

       3. Save the resulting ``.tar.gz`` (tarball) file somewhere
          it can be retrieved later when you want to image another
          machine.  This can be a network server, a USB drive,
          a DVD or whatever makes sense in your environment.  As
          with all backup systems, it's pretty important to make
          multiple copies of the backup image, and keep a couple
          of them off-site.


Provisioning With The Master Image

Now that we have a "snapshot" or master image, we can use it
to (re)provision machines.

    Provisioning Machines With A Master Image

       1. Boot the SUSE Linux installation disk and load the
          ``Rescue System``.

       2. Now we have to prepare the disk to receive a Linux
          filesystem.  The example below assumes we are installing on
          /dev/hda - a PATA master on the first IDE controller - but
          you can do what follows with any of the drives on your
          system.  Just substitute the device names as appropriate::

              # Partition the drive:

              fdisk /dev/hda

              # Delete and create partitions as you like
              # Make sure the partition that will mount /
              # is toggled to be bootable
              # Be sure to use the 'write' option before exiting

              # Suppose you end up with this:
              #    /dev/hda1  is for swap (type 82)
              #    /dev/hda2  is for your filesystem (type 83)

              mkswap /dev/hda1
              mkfs.reiserfs /dev/hda2
              mount /dev/hda2 /mnt

              # Now, let's create the top level directories that that
              # were not backed up and/or will be used by the kernel
              # for its own filesystems:

              cd /mnt
              mkdir dev media mnt proc sys tmp

              # Now it's time to mount your backup medium.  Depending
              # on your backup medium this can be one of several
              # devices.  CD/DVDs are often found at /dev/hdc1.  USB
              # drives show up as SCSI drives such as /dev/sda1, and
              # so on.  You'll also need to know the type of the
              # backup medium (see: man mount for the details):

              mount -tvfat /dev/sda1 /mnt/mnt  # This is a USB drive

              # OK, time to dump the image previously created by tbku
              # onto our shiny new filesystem (make sure your current
              # directory is still /mnt before doing this):

              tar -xzvf /mnt/my-system-image.tar.gz

              # Now we have to make sure that the boot tables and
              # default file mounts are correct - Our target system
              # may have a different drive type or device (SCSI, sata,
              # pata) than the system from which tbku took the image:

              # Edit /mnt/etc/fstab to reflect the partitioning
              # you did with fdisk.  Remember that drives can be
              # named by device name (/dev/xxxx) or by the vendor
              # name (/dev/disk/by-id/xxxx).  In our case the 
              # relevant portion of /mnt/etc/fstab looks like this:

              /dev/hda1    swap     swap       defaults         0 0
              /dev/hda2    /        reiserfs   acl,user_xattr   1 1

              # Be sure not to disturb the other stuff in the fstab
              # file

              # Now, check and fix the device map file,
              # /mnt/boot/grub/ Say we took the tbku image
              # from a system that boot from SCSI, that file
              # would look like this:

              (fd0)   /dev/fd0
              (hd0)   /dev/sda

              # But our new system wants to boot from ATAPI so it
              # now needs to look like this:

              (fd0)   /dev/fd0
              (hd0)   /dev/hda

              # We also have to correct any differences in the boot
              # menu that appears when you first start the system.
              # This is in /mnt/boot/grub/menu.lst  Near the top of
              # this file you'll see something like this:

              gfxmenu (hd0,1)/boot/message  

              # hd0 is right - we made sure of that when we edited
              # the map file above.  Make sure that the offset (1 in
              # this case) is also right.  This is the number,
              # *counting from 0* of the root/boot partition within that
              # drive.  In our case, (hd0,1) is correct because our
              # root/boot partition is /dev/hda2.

              # Following this are the individual menu entries.
              # Make sure you check each line of every entry.
              # Suppose we find this:

              title SLED 10 -
                  root (hd0,1)
                  kernel /boot/vmlinuz- root=/dev/sda2 
                        resume=/dev/sda1 splash=silent showopts
                  initrd /boot/initrd-

              # All references to /dev/sda2 have to be changed to /dev/hda2
              # All references to /dev/sda1 have to be changed to /dev/hda1
              # Repeat this for every menu entry.

              # Finally, lets make sure that the boot loader
              # is properly installed and configured:

              grub-install --root-directory=/mnt /dev/hda

We're DONE!  Well ... maybe.  If the hardware (chipset, CPU) of your
target machine is similar/same as the machine from which you took the
original image OR if the kernel you plan to boot has support for your
new target hardware, you should just be able to boot and run at this
point.  If not, read the following `Gotchas`_ section for further

This may all seem complex the first time you do it, but after a couple
of times, you'll be able to do this in your sleep.  Depending on how
large your backup image is, a complete system restore can typically be
done in less than an hour.  That's less than an hour to a *completely
configured system* with all your applications, custom configuration,
and so on as you last left them.


There are some circumstances where you cannot avoid doing some
configuration on the newly provisioned machine.

A. Network differences

B. Different Hardware

C. Different Chip Architectures


    Tim Daneliuk -

    Comments and/or improvements welcome!

Document Information

This document produced using the amazing ``reStructuredText`` tools in
the ``docutils`` package.  For more information, see:

``$Id: Imaging-SUSE-Linux-With-tbku.txt,v 1.104 2008/03/12 22:40:44 tundra Exp $``