L2J is an alternate game server for Lineage2. The L2 protocol is reimplemented in the server, so you can play with this server without any modifications to the client (except changing the server IP address). The latest USA live client version is always supported, so don't expect this server to work with the PTS/Korean client.
Plasma implements the map/reduce framework on a compute cluster. It has its own distributed filesystem, PlasmaFS, which is transactional (ACID), reliable, and fast, and which provides a complete set of file operations. PlasmaFS can be accessed via an RPC protocol or via NFS (i.e., it is mountable). Additionally, there is a key/value database on top of PlasmaFS.