Directory for Disk With Write-Once Storage Medium
Original Publication Date: 1987-Nov-01
Included in the Prior Art Database: 2005-Feb-02
From a logical standpoint, data on a disk is organized as "files" (or "data sets"). A directory relates this logical organization to the physical location of the data. From a physical standpoint, data is stored along a spiral that starts at the outside edge, for example, of the disk and ends at the inner edge. A "track" is one revolution of the spiral, starting and ending at a particular radius of the disk. A track is subdivided into physical units called "sectors". Each track has the same number of sectors, and corresponding sectors start on the same radius. Some sectors may be unusable because the storage material is defective or because these sectors have been logically erased, but the disk medium cannot actually be erased or rewritten.