How do I set up a Red Hat Enterprise Linux 6 diskless client sharing the OS image?

Issue

Solution provided in article:
How do I set up a Red Hat Enterprise Linux 6 diskless client?

gives us after diskless client is netbooted rootfs which is common between all clients:

# df -h
Filesystem            Size  Used Avail Use% Mounted on
10.0.0.105:/data/iso
                      2.4G  2.4G     0 100% /
tmpfs                  32G     0   32G   0% /dev/shm

Changes to one client would be applied to nfs-rootfs of all systems using this image.

client1

[root@client1 ~]# touch /test

[root@client1 ~]# ls -l /test
-rw-r--r-- 1 root root 0 Nov  4 00:06 /test

client2

[root@client2 ~]# ls -l /data/iso/test
-rw-r--r-- 1 root root 0 Nov  4 00:06 /data/iso/test

How can we setup a Red Hat Enterprise Linux 6 diskless client sharing the same OS image?