I am currently using memcached with my java app, and overall it\'s working great.
The features of memcached that are most important to me are:
EhCache has a "disk persistent" mode which dumps the cache contents to disk on shutdown, and will reinstate the data when started back up again. As for your other requirements, when running in distributed mode it replicates the data across all nodes, rather than storing them on just one. other than that, it should fit your needs nicely. It's also still under active development, which many other java caching frameworks are not.