One or more storage units that are defined from the disc units or disk-unit subsystems that make up addressable disc storage. disc pools (which are also known as auxiliary storage pools ) provide a means of placing certain objects on specific disc units to limit the impact of disk-media failures and to reduce recovery time. A basic disc pool contains both objects and the libraries or directories that contain the objects. Attributes such as authorization, ownership, and spooled file attributes are stored in the system disc pool (also known as the system ASP).