Abstract: Methods and apparatus are described for a data transfer unit between a storage unit and a host, wherein a slower data transfer rate is established when a predetermined error is detected. In one embodiment the cyclicity of the error occurrence calculated and a wait is inserted between data to avoid transferring data at the calculated cyclicity point of the detected error. Optionally the data transfer unit may return the data transfer rate to the original data transfer rate or state after a predetermined time has elapsed, after a predetermined number of commands have been received, after a predetermined amount of data have been transferred, or by combination of these.

Abstract: A disk drive unit and an error recovery method for the disk drive unit which can reduce processing time for ERP in resetting, thereby shortening response time to the reset is described. A normal error recovery procedure is executed if there is no reset request when a write error occurs, but if there is a reset request pending, a data record in which a write error occurs is registered as a defective position (e.g. sector) and an alternate (spare) position is assigned to accelerate the time when the drive can respond to the reset instruction. Data records with alternate positions assigned as a part of the reset activity are specially marked so that alternate position assignment can be undone as soon as is appropriate, for example, when the record is next read or written.

Abstract: A disk drive and a method for controlling the disk drive in which an additional read from a medium can be performed as needed while minimizing the command overhead to the minimum. In a disk drive device 10, even if a read command is issued, and all the required data is stored in the cache memory such that the data transfer can be performed without the intervention of a local MPU 16, a HIC 15 performs the data transfer so as to leave the last one block and waits for the intervention of the local MPU 16. The local MPU 16 provides instructions to transfer the last one block when the preparation for the command termination is completed, and if a plurality of blocks of data to be transferred are remaining when the local MPU 16 instructs the HIC 15 to transfer the last one block, the HIC 15 executes all the data transfer without stopping the data transfer before the last one block, completing the command.