Abstract: To provide a method of starting a data storage unit which allows a computer system to be used as early as possible. The present invention relates to a method for starting up a computer system having a data storage unit equipped with an actuator arm which supports a flexible cable. The method allows a command from the host computer to be processed before generation of corrected tension data for the flexible cable. The method includes the steps of turning on power; executing a start operation, excluding generation of corrected tension data of the flexible cable; causing an access command from a host computer to be in an executable state, following the step of executing a start operation; and executing generation of corrected tension data of the flexible cable, following the step of causing an access command from a host computer to be in an executable state.

Abstract: Method and apparatus are described for recovery from temporary errors in a disk drive resulting from excessive temperature or the like. After a first error recovery procedure has been executed and failed, a waiting time is selected after which a second error recovery procedure will be performed. The length of the waiting time can be determined by the measured temperature if a sensor is included in the drive. If the error still cannot be recovered after the waiting period, the location where the error had occurred is temporarily registered as defective. Subsequently the drive will retest the failing location and remove the temporary defect registration if the error has been removed by, for example, the temperature having gone down.

Abstract: The present invention provides a disk drive device containing a cache memory having K queue entries (K is an integer) to operate in a write cache mode and a method for controlling the disk drive device. The number of the queue entries to be used in the write cache mode can be gradually decreased from the number K to a decreased number by a predetermined number, and the number of the queue entries to be used in the write cache mode can be gradually increased from the decreased number towards the number K by a predetermined number, in response to values of parameters, such as an error rate and Non Repeatable Run Out or Repeatable Run Out of the rotating data recording disk at writing of data from the cache memory to a rotating data recording disk.

Abstract: A method and apparatus for improving the data readability in a disk drive is described. The disk drive uses an error recovery mode in which the rotational speed of the motor is decreased below the normal operating speed and a rereading is performed. The reduced speed lowers the energy generated in collisions with a foreign object and the data error length is shortened allowing data to be read which cannot be read at the normal operating speed.

Abstract: The present invention provides a method and apparatus to efficiently switch heads in a disk drive. A disk drive comprises a plurality of recording surfaces and a plurality of heads and each head is opposed to a recording surface. The heads are used for reading data from or writing data to the plurality of recording surfaces. An offset quantity table stores an offset quantity for each of the plurality of heads. The offset quantity is a value representative of the distance of a head with respect to a reference head. A head sequence table stores a predetermined head switching sequence. Head switching operations use the head switching sequence stored in the head sequence table.