OCFS2 is for multiple clients and not data clusters. Yes one can use DRBD with OCFS2, but on its own OCFS2 is just a cluster aware file system with locking. It knows that more than one node will be accessing the same disk and uses file locking.
It works perfectly well with a shared disk on multiple web nodes, I have built dozens of Moode setups using 2 x web nodes both sharing a disk across a SAN using OCFS2