I don't know how good Heartbeat is these days. I'm just going based on our experience back then and GitHub's stated experience now.

We (in a new place) use our own fail over code now, but we're running databases instead of file servers -- and you usually don't want to STONITH a database.

For file servers we use Gluster, and it works great for us (I'm sure there are reasons GitHub are doing active-passive DRBD) and you don't need STONITH since it's shared-nothing.