Various features require persistence.
A volatile RAM based storage mainly used for development purposes. Can also be used where the storage is not required to persist between process restarts.
Uses the RavenDB document database for storage.
Uses custom NHibernate to persist data to an ADO.net data store (e.g. SQL Server).
A subscription only storage on top of MSMQ.
Uses Azure Tables Storage for storage
Uses Json.NET to serialize data and store in a SQL database.
There are several community run Persistences that can be seen on the full list of Extensions.