Short example on restoring from a backup. 

Normally I create at least 2 partitions on the harddisk and can install
2 (or more operating system). These note show how to restore from a
backup (located in /irtf.backup). 

1. On the target computer boot from the CD or the other partition.
   Format the target parition, then mount

   # mkfs -V -t ext3 /dev/hda7
   # mount /dev/hda7 /r0

2. Restore from backup (to /r0).

   # cd /r0
   # restore -rf /irtf.backup/HOST/YYMMDD.root.zdump

3. Update configuration (if needed).

      /etc/hosts
      /etc/sysconfig/network
      /etc/sysconfig/network-scripts/ifcfg-eth0
      /etc/fstab
      /etc/X11/xorg.conf

   Boot from new parition:
      - modify grub menu and boot. (root should be hda7 & running centOS 2.6.9-11.EL).
      - reset root passwords.

4. reinstall grub.
 
   # grub
   grub> root (hd0,6)  <- hda7 is hd0,6
   grub> find /boot/grub/stage1
   grub> setup (hd0)
   grub> quit