CentOS - Mar 2013 - GFS2 hangs after one node going down

Hi guys,

my goal is to create a reliable virtualization environment using CentOS 
6.4 and KVM, I've three nodes and a clustered GFS2.

The enviroment is up and working, but I'm worry for the reliability, if 
I turn the network interface down on one node to simulate a crash (for 
example on the node "node6.blade"):

1) GFS2 hangs (processes go in D state) until node6.blade get fenced
2) not only node6.blade get fenced, but also node5.blade!

Help me to save my last neurons!

Thanks
Maurizio