Dynamic hierarchies and optimization in distributed storage systems

The authors propose techniques to allow controlled penetration of the location transparencies of a distributed storage system by generalizing the simple disk-tape hierarchy paradigm of current storage systems to include multiple co-existing dynamic storage hierarchies. An orthogonal, semantics-free optimization primitive is proposed to manipulate the relation between an object and its hierarchy. By managing the hierarchy attribute of a storage object and a systemwide configuration of storage device hierarchies, one can position objects on any desired set of devices without destroying the fundamental transparencies of the system. The level of detail concerning the storage location of an object can range from general (somewhere in the 'fast' storage hierarchy) to very explicit (a specific disk drive). >