Abstract: A system including first and second memory and a control module. The first memory stores a first lookup table with first metadata that includes a first mapping between logical and physical addresses and is lost due to an unexpected power down event. The second memory stores a second lookup table with second metadata and an event log. The second metadata includes a second mapping between the logical and physical addresses. The event log includes entries indicating updated associations between respective ones of the logical addresses and one of the physical addresses as included in the first metadata prior to the power down event. The control module: prior to the power down event, performs segmented flushes each including updating a segment of the second metadata with a corresponding segment of the first metadata; and walks the event log to recover a full flush cycle of segments of the first metadata.

Abstract: A storage module includes a first memory with blocks for storing first and second commands transmitted from a host to a storage module. The staging module determines, based on a first timer, whether the first command has been received from the host. If received, the first command is stored in a first block of the first memory. If not received, the first block is left empty. A timing module starts the first timer when the first block is left empty and starts a second timer for the first block when the first command is stored in the first block. A control module: executes the commands to transfer data between the host and a second memory based on storage of the commands; determines whether a second block is empty; if empty, waits for the second timer to expire; and if not empty, resets the first timer.

Abstract: A system including first and second memories and a control module. The first memory stores a first lookup table (LUT) with first metadata. The first metadata maps logical addresses to physical addresses. The first metadata is lost due to an unexpected power down event. The second memory stores an event log and a second LUT with second metadata. The second metadata maps the logical addresses to the physical addresses. The event log includes entries that indicate updated associations between the logical addresses and the physical addresses. The control module, prior to the unexpected power down event, performs segmented flushes that include updating segments of the second metadata with segments of the first metadata.

Abstract: Methods and apparatus for temporarily storing parity information for data stored in a storage device are provided. A first data block and parity information associated with the first data block are received. The first data block is stored in a first region of the storage device. The parity information is stored until a second data block is successfully stored in a second region of the storage device. The first region of the storage device is associated with the second region of the storage device.

Abstract: A system includes a first memory configured to store a first lookup table (LUT) with first metadata. A second memory is configured to store a second LUT with second metadata, wherein the first metadata includes a first mapping between logical addresses and physical addresses. The second metadata includes a second mapping between the logical addresses and the physical addresses. A control module is configured to update the first metadata. The control module is configured to update segments of the second metadata based on the first metadata at respective predetermined times. Each of the segments refers to a predetermined number of entries of the second LUT.

Abstract: Methods, systems, and apparatus, including computer program products, are described for calibrating servos, and in some implementations for calibrating spiral servos for use in self servo write processes. In one aspect, a method is provided that includes measuring a slope of a spiral written to a machine readable medium, and adjusting a parameter in accordance with the measured slope to calibrate spacing of servo tracks, with respect to variation between a target slope and the measured slope for the spiral, for writing the servo tracks to the machine readable medium using the spiral as a reference and the adjusted parameter to generate a same radial spacing between servo tracks from spirals with different slopes.

Abstract: Methods and apparatus for temporarily storing parity information for data stored in a storage device are provided. A first data block and parity information associated with the first data block are received. The first data block is stored in a first region of the storage device. The parity information is stored until a second data block is successfully stored in a second region of the storage device. The first region of the storage device is associated with the second region of the storage device.

Abstract: A drive control module of a solid-state drive (SSD) includes a first module that receives host commands from one of a host command buffer and a drive interface of the SSD, converts the host commands to stage commands, and determines whether to store the stage commands in a stage slot of a staging memory or leave the stage slot empty. A second module transfers data between a buffer and a flash memory based on the stage commands. The flash memory comprises flash arrays. A third module detects a first empty stage of one of the flash arrays and based on an empty stage timer value triggers at least one of an end of the first empty stage, a start of an at least partially full stage of the one of the flash arrays, or a start of a second empty stage of the one of the flash arrays.

Abstract: Systems, methods, and apparatuses, including computer program products, are described for, in at least one implementation, determining a measured slope of a spiral, calibrating radial spacing between servo tracks according to a relationship between a target slope and the measured slope, wherein an amount of calibration for the radial spacing varies directly with the relationship between the target slope and the measured slope, and generating servo tracks according to the calibrated radial spacing.

Abstract: A system includes a first memory configured to store a first lookup table (LUT) with first metadata. A second memory is configured to store a second LUT with second metadata, wherein the first metadata includes a first mapping between logical addresses and physical addresses. The second metadata includes a second mapping between the logical addresses and the physical addresses. A control module is configured to update the first metadata. The control module is configured to update segments of the second metadata based on the first metadata at respective predetermined times. Each of the segments refers to a predetermined number of entries of the second LUT.

Abstract: Methods, systems, and apparatus, including computer program products, are described for calibrating servos, and in some implementations for calibrating spiral servos for use in self-servo-write processes. In one aspect, a method is provided that includes determining a measured slope of a spiral, and calibrating radial spacing between servo tracks using the measured slope and a target slope.

Abstract: Methods of compensating for repeatable runout in a disk drive are provided. The disk drive includes a data storage disk, a transducer adjacent to the disk, a primary actuator for positioning the transducer over a first range of movement, and a secondary actuator for positioning the transducer over a second range of movement that is less than the first range of movement. Estimates are made of the position of the secondary actuator in the second range of movement. Data is read from the disk via the transducer. A position error signal is determined based on the read data. Positioning of the transducer by the primary actuator is controlled based on the estimated position of the secondary actuator in the second range of movement and based on the position error signal to compensate for repeatable runout.