rsk writes "Since the Ubuntu One desktop synchronization service was launched by Canonical it has always been powered by CouchDB, a popular document-oriented NoSQL data store with a powerful master-master replication architecture that runs in many different environments (servers, mobile devices, etc.). John Lenton, senior engineering manager at Canonical, announced that Canonical would be moving away from CouchDB due to a few unresolvable issues Canonical ran into in production with CouchDB and the scale/requirements of the Ubuntu One service. Instead, says Lenton, Canonical will be moving to a custom data storage abstraction layer (U1DB) that is platform agnostic as well as datastore agnostic; utilizing the native datastore on the host device (e.g. SQLite, MySQL, API layers, 'everything'). U1DB will be complete at some point after the 12.04 release."
You can tune a piano, but you can't tuna fish.
You can tune a filesystem, but you can't tuna fish.
-- from the tunefs(8) man page