At my job at OpenSky we have a common NFS share that is failed over to a slave nfs node if the master dies. It was setup so that the slave would just rsync from the master. This was done to save time. Not that I have some time, I decided to finally setup drbd on the two nodes to keep the files always in sync.
To look something like this. You will want to change a few things in red. Put this file on both nodes.
Once you start drbd on both nodes it will connect to both. If you just start one and not the other.. the other will wait for the second node to come alive.
You can now make a filesystem. Make sure it is a filesystem for clustering. I recommend ocfs2 but gfs2 also works.