Even if you have identical hardware on your machines, there are certain locations that should remain unique in order for your system to function.
Here are some things you should not mirror, even if you have identical hardware.
- /dev/
- /etc/udev/
- /etc/hostname
- /etc/networking/interfaces
- /proc/
- /sys/
You probably do not want to mirror these, but that will vary.
- /home/
- /root/
- /var/log/
Also, if you are running a linux high availability cluster, you will need to exclude these.
- /var/lib/heartbeat/hb_uuid
- /etc/ha.d/*.pem
Nothing Fancy 
2 Comments
If you are running a RedHat based distro, you need to exclude
– /etc/sysconfig/
Apparently, RedHat based distros generate most other cfg stuff from that directory, so you might not need to worry about /etc/udev/ /etc/hostname and /etc/networking/interfaces.
That last note has been verified; you don’t need to worry about /etc/udev/ /etc/hostname and /etc/networking/interfaces on RedHat.