we have a vcs cluster set up and noticed that they were showing one of the heart beat link qfe3 as DOWN. Both qfe2 and qfe3 were fine all along, btw if I were to push in/re-set the hb cable, do you know whether it will panic or cause anything to the system,? Its a DB critical prod nodes

It shouldn't if you only reset one of the heartbeats at a time. I can't help but notice though that you are running both heartbeats on a single card which is not exactly the best of designs.

A week back one of the nodes dropped to single user all of a sudden. No helpful messages or logs were captured. esc case to Sun, Veritas but they informed they could find nothing wrong. At that time, I did not check on the heartbeat. Only came across when I had to do patching activity on the nodes yesterday. That's why Im suspecting whether this was the reason that caused the one of the node to go down....

You also may want to freeze your service groups before you do this.