Doubts about storage

I'm still learning the technologies available on the market, so I'm not sure wich of them I will use. Now I'm learning about storage solutions like SANs, mulipath, network and clusterd file system, in details I'm deciding if and how I can setup a SAN with iSCSI and wich file system build upon it, if GFS2 (global file system from Sun) or NFS.

Consider that by now I'm still a little confused between the various solutions.

The simpler solution would be setting up only one server with its RAID hard drives for drive redundancy an NFS coupled with DRBD on the secondary server in an Active/Passive architecture synched with the primary server. But as I said I want load balacing, so I need an Active/Active, but I don't know if is it possible to achieve this with DRBD and if yes in wich way.

I like to get involved in more advanced situations so I would like to learn how to use SAN. In this case the solution would be to build a SAN wich expose its storage with iSCSI and then build on top of the SAN or NFS again or a Global File System v2 in every node of the cluster. But my problem is that I'm not sure how to build a SAN (but I feel I need only some practice) and how GFS2 is structured or, in other words, how to distribute it over the nodes of the cluster and how they will use it. Google is waiting for me.