The SPPersistedObject class provides a base class for all administration objects. It serializes all fields marked with the Persisted attribute to XML and writes the XML blob to the configuration database. The SPPersistedObject class contains code to serialize all its members that are base types, other persisted objects, and collections of persisted objects. Configuration data that is stored in persisted objects is automatically made available to every process on every server in the farm.
When you create a custom persisted object you must specify the default constructor for serialization.
To return an existing persisted object, use the GetObject method of the SPFarm class, or the GetChild method of the SPPersistedObject class.