Abstract: Systems and techniques relating to servo systems include, according to an aspect, a method includes: causing writing of a band of spirals including a first spiral set and a second spiral set onto a storage medium; determining one or more characteristics associated with the band of spirals; identifying one or more spirals of the band of spirals that meet the one or more determined characteristics; and determining an end of the band of spirals based on the one or more identified spirals. The method can further include causing writing of servo information onto the storage medium while track following on the band of spirals; causing terminating of the writing of the servo information upon determining the end of the band of spirals; and causing writing of another band of spirals starting at the end of the previous band of spirals.

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: Embodiments of the present disclosure provide apparatuses and methods for determining a compacting arrangement to store logical addressable units, which include compressed data sectors, into hardware addressable units of a storage device. The compacting arrangement is based on compression information associated with the logical addressable units. A write module is used to write the compressed data sectors to the storage device according to the compacting arrangement.

Abstract: Methods, systems and computer program products for detecting an end of a reference spiral band are described. A first portion of servo information may be written on a disk using the reference spiral band. By detecting an end of a reference spiral band, a new reference spiral band may be launched. A read/write head of a hard disk drive may subsequently use the new spiral band to write the remaining portion of the servo information, which aids the writing of data tracks on the disk.

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: Embodiments of the present disclosure provide a method including recording time stamps for a repeating characteristic of a spindle back electromotive force (BEMF) signal and comparing one or more of the recorded time stamps for the repeating characteristic of the spindle BEMF signal with an expected value for the one or more recorded time stamps to detect a timing error associated with writing a servo pattern on a machine readable medium of a self-servo write (SSW) system. Other embodiments may be described and/or claimed.

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: Apparatus, methods, and systems can be employed for calibrating servos, and in some implementations, spiral servos are calibrated for use in self-servo-write (SSW) processes. In an aspect, an apparatus includes a timing reference detector configured to determine timing reference information from a back electromotive force signal associated with a rotating machine readable medium, and a servo track window period generator configured to determine a relative location of a spiral on the rotating machine readable medium based on the timing reference information.

Abstract: Embodiments of the present disclosure provide apparatuses and methods for determining a compacting arrangement to store logical addressable units, which include compressed data sectors, into hardware addressable units of a storage device. The compacting arrangement is based on compression information associated with the logical addressable units. A write module is used to write the compressed data sectors to the storage device according to the compacting arrangement.

Abstract: Embodiments of the present disclosure provide a method including recording time stamps for a repeating characteristic of a spindle back electromotive force (BEMF) signal and comparing one or more of the recorded time stamps for the repeating characteristic of the spindle BEMF signal with an expected value for the one or more recorded time stamps to detect a timing error associated with writing a servo pattern on a machine readable medium of a self-servo write (SSW) system. Other embodiments may be described and/or claimed.

Abstract: Methods, systems and computer program products for detecting an end of a reference spiral band are described. In some implementations, a band of spirals and servo information are written onto a storage medium. One or more characteristics associated with the band of spirals are determined. Then, one or more spirals of the band of spirals are identified as reference spirals based on the one or more determined characteristics. The writing of at least one of the band of spirals and the servo information is terminated upon identifying the one or more reference spirals.

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: Methods, systems, and apparatus, including computer program products are described for calibrating servos, and in some implementations, calibrating spiral servos for use in self-servo-write (SSW) processes. In one aspect, a method is provided that includes determining timing reference information on a machine readable medium, locking a clock signal to the timing reference information, detecting a spiral on the machine readable medium, determining a location of the spiral using the clock signal, and calibrating a spiral servo according to the location of the spiral.

Abstract: Methods, systems and computer program products for compensating repeatable run-out (RRO) are described. In some implementations, RRO may be compensated by predicting the RRO and subsequently subtracting the predicted RRO from the actual value of the RRO to cancel out the undesired effect caused by the RRO during operation. More specifically, RRO generated at each spindle motor rotation may be predicted by measuring the position errors associated with the RRO with respect to a current position of a read/write head. A computational model then may be utilized to determine one or more correction factors to compensate for the RRO.

Abstract: The present disclosure includes systems and techniques relating to magnetic recording devices, such as disk drives. A recording medium of a magnetic recording device can include multiple helicoid patterns arranged in multiple helicoid groups. A described technique includes receiving a waveform produced by a head operated with respect to the medium; determining, based on the waveform, first phase difference(s) corresponding to a first helicoid group; affecting an alignment of the head with respect to the medium based on the first helicoid group by compensating for the first phase difference(s) to maintain the alignment; determining, while compensating for the first phase differences, second phase difference(s) corresponding to a second helicoid group; and affecting, responsive to a switch from the first helicoid group to the second helicoid group, the alignment of the head with respect to the medium by compensating for the second phase difference(s) to maintain the alignment.

Abstract: Methods, systems, and apparatus, including computer program products are described for calibrating servos, and in some implementations, calibrating spiral servos for use in self-servo-write (SSW) processes. In one aspect, a method is provided that includes determining timing reference information on a machine readable medium, locking a clock signal to the timing reference information, detecting a spiral on the machine readable medium, determining a location of the spiral using the clock signal, and calibrating a spiral servo according to the location of the spiral.

Abstract: Methods, systems, and apparatus, including computer program products are described for calibrating servos, and in some implementations, calibrating spiral servos for use in self-servo-write SSW processes. In one aspect, a method is provide that includes rotating a machine readable medium, and detecting a spiral on the machine readable medium. Detecting a spiral on the machine readable medium includes detecting magnitudes of the spiral and a timing mark, storing a timestamp from a clock signal that corresponds to the timing mark of the spiral, determining a peak of the spiral from the magnitudes, and locking the clock signal to the peak of the spiral using the timestamp.

Abstract: A method for dynamic spiral ISR scheduling determines a dynamic delay with spiral to spiral spacing information of a disk, so as to ensure that the sum of a primary ISR time and a secondary ISR time does not exceed the wedge to wedge time. The ISR time may be scheduled to start after a delay for the sum of a static delay and the dynamic delay from an edge. A system for dynamic spiral ISR scheduling uses a dynamic delay determining unit to determine a dynamic delay, and an ISR scheduling unit to schedule the start of a secondary spiral set ISR based on a sum of the dynamic delay and a static delay.

Abstract: A servo control system includes an input that receives spiral signals generated by reading spirals that are prewritten on a magnetic medium. The servo control system further includes a control module that generates spiral correction values for the spirals based on the spiral signals and that determines positions of the spirals based on the spiral correction values.

Abstract: A recording medium can include multiple helicoid patterns arranged in multiple helicoid groups, e.g., first and second helicoid groups. Operating a disk drive can include switching between helicoid groups to maintain the alignment of the head with respect to a target track of the rotating recording medium. Enabling a switch can include receiving a waveform produced by a head operated with respect to a rotating recording medium, generating first information from one or more portions of the waveform corresponding to the helicoid patterns of the first helicoid group; generating second information from one or more portions of the waveform corresponding to the helicoid patterns of the second helicoid group; and analyzing the second information with respect to the first information to generate calibration information. The calibration information can compensate for operational differences between using the helicoid patterns of the first helicoid group and the helicoid patterns of the second helicoid group.