Abstract: Disclosed are improved methods, devices and systems for storage management in digital networks.

Abstract: In a disk mass storage facility for data processing systems, a disk format which improves handling of defective segments of medium and reduces access time. The format has three layers. A first, physical layer comprises the bytes, sectors and collections of sectors, as well as error detection and correction codes. A second, logical layer is used to address the physical layer and to collect together sectors to form a multiplicity of separately addressable spaces, with each space having a distinct functional utility. At a third, functional layer the use of data fields in each space is specified. This layer governs the handling of bad blocks if required, and the use of certain format information. Handling of bad blocks is controlled by a hierarchically layered process. A portion of each disc, distributed across the medium, is reserved as spare sectors to replace defective sectors. After a bad sector is replaced, future attempts to access the bad sector are redirected (i.e., revectored) to the replacement sector.