Disk drive employing dynamically reconfigured read channel to process a read signal at two different frequencies

摘要

A disk drive having an embedded servo disk format preferably having a fixed-number of radial servo sample wedges per track, in which data blocks are located independently of the servo sample wedge locations of any particular track, and can be split around servo sample wedges. Thus, a fraction of a data block, or more than one data block, can be written between consecutive servo sample wedges, beginning almost anywhere in a data wedge. Each data sector has an associated identification (ID) field that includes at least one segment descriptor. Each segment descriptor describes the data segments into which a data block can be split. Provision is made for as many segment descriptors as there can be data segments for a data block. In general, a segment descriptor is a multi-bit digital signal that defines the absolute or relative location of split data segments (or, alternatively, the absolute or relative length of split data segments, from which the location can be determined). A disk system in accordance with the present invention can be independently optimized for flux changes per inch and tracks per inch, and the size of each data sector can be varied. The invention permits "defect swallowing", by allowing a data sector to be split around small defects within a data wedge of a track, and "wedge push down" defect management, in which a data segment can be started at a next servo sample wedge if a large defect occurs in the previous data wedge.