MULTIPLE ID FIELD SECTOR FORMAT.

Direct-access storage devices (DASDs) with fixed block architecture (FBA) formats divide the storage space into small blocks of fixed length usually called sectors. Each sector contains an ID field and a data field. The recording surface can be defective in either the ID field or the data field. Till now, when the defect occurred in the ID field within a sector, the ID was again written in the data field displaced 64 bytes from the normal ID location. In the present arrangement, when a sector is determined to be defective, the ID is written in the normal ID position and eight times within the data field, spaced 64 bytes apart.