Abstract: An adaptive maximum seek velocity clipping technique is employed in a disk drive to reduce head movement power requirements. Separate maximum seek velocities are established for respective categories of access commands, where the categories are defined by seek distance and estimated extra latency. The maximum seek velocity established for each category of access commands reflects actual experience in executing access commands of the given category. The maximum seek velocity values for the various categories are stored in a maximum seek velocity table, which is referred to upon execution of access commands. The inventive power-saving technique may be advantageously applied in conjunction with a probability-based shortest access time first (SATF) command queue ordering algorithm.

Abstract: A method and apparatus are provided for efficiently sorting queued commands with unknown rotational latency in a direct access storage device (DASD). For each command an initial expected access time (EAT) including a probability of success calculation is calculated and stored in a miss table. An actual starting location for the next command to be executed is identified. Utilizing the miss table, and a calculated best candidate command list for a plurality of different starting locations, a command in a command queue is selected based upon the actual starting location. The best candidate command list for a plurality of different starting locations is calculated by first sorting the miss table row by increasing EAT values and sequentially incrementing a miss time value by the predefined unit of time and updating all variable in the first row and adjusting a potential value in the second row of the miss table.

Abstract: An adaptive maximum seek velocity clipping technique is employed in a disk drive to reduce head movement power requirements. Separate maximum seek velocities are established for respective categories of access commands, where the categories are defined by seek distance and estimated extra latency. The maximum seek velocity established for each category of access commands reflects actual experience in executing access commands of the given category. The maximum seek velocity values for the various categories are stored in a maximum seek velocity table, which is referred to upon execution of access commands. The inventive power-saving technique may be advantageously applied in conjunction with a probability-based shortest access time first (SATF) command queue ordering algorithm.

Abstract: A method and apparatus are provided for efficiently sorting queued commands with unknown rotational latency in a direct access storage device (DASD). Simultaneously with executing a current command, for each command in a DASD command queue an initial expected access time (EAT) including a probability of success calculation is calculated and stored together with a plurality of predefined variables in a respective row in a miss table. Utilizing the stored miss table, a best candidate command list for a plurality of different starting locations for a next command to be executed is calculated. An actual starting location for the next command to be executed is identified. Utilizing the best candidate command list for the plurality of different starting locations, a command in a DASD command queue is selected based upon the actual starting location.