Changing the entire question as earlier one was very confusing.
I have been exploring different clustering system to run Virtual machines on two different machines on LAN with high availability.
Currently I am already using DRBD resource on two different machines on Primary/Secondary mode. In case the primary fails I manually promote the secondary to Primary and start the VM.
I also explored Gluster and looks good, however, I would rather prefer clustering over Gluster (user space FS).
So if anyone has idea which one would be better from ease of use prospective please I would be interested in.
Moreover, sheepdog project appears good, however, could not find much documentations/Howtos.
I am using Centos 6.