Stmicroelectronics Gmbh

Stmicroelectronics N.v.

Russell B Josephson

Aaron Wade Wilson

Wen Lin

Rodney A Mattison

Wayne Aaron Thorsted

A method, and a system for implementing such method, for use in a magnetic disk storage system for compensating for variation in spin speed of a data storage media from a nominal or design spin speed. The method includes providing the nominal spin speed for the data storage media in the particular magnetic disk storage system and then measuring the actual spin speed of the data storage media. In one preferred embodiment, the spin speed measurement is completed by measuring the time from one servo position field to the next sequential servo position field in a track on the data storage media. Next, the present spin speed variation is determined by comparing the measured spin speed with the nominal spin speed. A correction factor is calculated based on the spin speed error and applied to at least one data transfer parameter, such as channel reference frequency or read/write gate assertion timing, prior to a subsequent data transfer process (i.e., a read or a write operation). The spin speed compensation method may further include verifying that the measured spin speed is within a range of acceptable spin speeds. The range of acceptable spin speeds is determined based on maximum spin speed change rates of the magnetic disk storage system and the most recent measured spin speed. If the measured spin speed is outside this range, the data transfer operation, i.e., a write operation, is stopped to prevent damaging data previously stored on the data storage media.

Method and system for compensation for spin speed variation in a magnetic disk storage device

A system for halting operation of a hard disk controller when a write operation occurs during a servo positioning error condition including a memory cell for retaining an indication of whether a write operation occurred during the previous servo sector. A memory cell, such as a flip flop, is set on any occurrence of a write operation. With the reading of a next servo field, the output of the first flip flop is latched to a second flip flop. During a present servo sector, a servo positioning error signal is logically AND'ed with a write gate active signal where the write gate active signal is enabled if write gate is active in the present servo sector or write gate was active in the previous servo sector (as indicated by the output from the second flip flop.

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Berthoud, CO, United States of America

Russell B Josephson