Abstract: A disk drive is disclosed wherein a plurality of access commands received from a host are stored in a command queue. An access cost for at least a first and second access command in the command queue is generated, wherein each access cost comprises a seek length and a rotation latency. A first access command is selected from the command queue having a first access cost, and a window is defined relative to the first access cost and a first risk based penalty (RBP) of the first access command, wherein the first RBP represents a probability of missing a first data sector of the first access command. A second access command is selected from the command queue comprising a second access cost within the window. A choice is made between the first and second access commands in response to a second RBP of the second access command.

Abstract: An apparatus comprises a storage medium, an arm for positioning a recording head adjacent to the storage medium, and a controller for receiving objects and for selecting blocks on the storage medium to be written by the recoding head based on information in the objects. A method for storing objects is also provided. In another aspect, the invention provides a method for writing data in data storage devices. The method comprises: receiving access commands for objects, selecting blocks on a storage medium to be written by a recording head based on information in the objects, and writing data from the objects to the selected blocks.

Abstract: Method and apparatus for transferring data between a host device and a data storage device having a first memory space (such as a buffer) and a second memory space (such as magnetic discs). Data are stored on the discs in host-addressable data sectors. The data storage device is configured to operate in a local mode of operation and a nonlocal mode of operation. During the local mode, nonrequested user data are retrieved from the discs and placed into the buffer in anticipation of a future request for the nonrequested user data. During nonlocal mode, such nonrequested user data are not retrieved. An interface circuit monitors host data access patterns and dynamically switches between the nonlocal and local modes in relation to proximity of a data sector address of each most recently received read command to data sector addresses associated with previously received read commands.

Abstract: Method and apparatus for transferring data between a host device and a data storage device having a first memory space and a second memory space. The host issues access commands to store and retrieve data. The device stores commands in the first memory space pending transfer to the second memory space. An interface circuit evaluates relative proximity of first and second sets of LBAs associated with pending first and second commands, and delays promotion of later pending commands in front of earlier pending commands during an overlap condition. If the overlap is caused by performance enhancing features (PEF) the PEFs are disabled so the commands can be scheduled for disc access. Indicators are set in the commands to signal that a PEF has caused the overlap and that PEF can be disabled. Values are added to indicators in the commands such that the PEFs can be modified and avoid overlaps.

Abstract: Apparatus and method for improving disc drive performance by compensating for head-to-head offsets when scheduling a plurality of pending access commands. A disc drive includes a plurality of recording surfaces on which a plurality of concentric data tracks are defined. A servo circuit performs seeks to move a plurality of heads from an initial track to a destination track. A positional offset between each of the plurality of heads is measured and applied to an estimated seek length to calculate a corrected seek length. A corrected seek time is calculated from a seek profile table in relation to corrected seek length. The corrected seek time is used by a control processor to schedule the access commands stored in the memory.

Abstract: Method and apparatus for transferring data between a host device and a data storage device having a first memory space (such as a buffer) and a second memory space (such as magnetic discs). Data are stored on the discs in host-addressable data sectors. The data storage device is configured to operate in a local mode of operation and a nonlocal mode of operation. During the local mode, nonrequested user data are retrieved from the discs and placed into the buffer in anticipation of a future request for the nonrequested user data. During nonlocal mode, such nonrequested user data are not retrieved. An interface circuit monitors host data access patterns and dynamically switches between the nonlocal and local modes in relation to proximity of a data sector address of each most recently received read command to data sector addresses associated with previously received read commands.

Abstract: Method and apparatus for transferring data between a host device and a data storage device having a first memory space and a second memory space. The host issues access commands to store and retrieve data. The device stores commands in the first memory space pending transfer to the second memory space. An interface circuit evaluates relative proximity of first and second sets of LBAs associated with pending first and second commands, and delays promotion of later pending commands in front of earlier pending commands during an overlap condition. If the overlap is caused by performance enhancing features (PEF) the PEFs are disabled so the commands can be scheduled for disc access. Indicators are set in the commands to signal that a PEF has caused the overlap and that PEF can be disabled. Values are added to indicators in the commands such that the PEFs can be modified and avoid overlaps.

Abstract: A disc drive includes a base and a disc rotatably attached to the base. The disc drive also includes an actuator assembly rotatably attached to said base and a device for moving the actuator assembly. The actuator assembly includes a transducer head in a transducing relationship with respect to the disc. The disc drive includes a disc drive controller for controlling movement of the actuator during track follow and track seek operations. The disc drive controller computes a phase difference time when a command is generated to complete a seek. When a seek is performed, the disc drive controller computes the phase difference time. Then the controller monitors the actual seek time, and adjusts the phase difference time based on a comparison of the actual seek time with the computed phase difference time.