Abstract:
A method involves determining a threshold error rate that will result on data stored on a magnetic disk surface of a disk drive being unrecoverable. The method also involves determining a seek velocity that will overwrite sufficient portions of the data such the data will exhibit at least the threshold error rate. The disk drive performs at least one traversal of the magnetic disk surface with a head of the disk drive that emits an erase field during the at least one traversal at the seek velocity. The at least one traversal sanitizes the data.
Abstract:
The technology disclosed herein pertains to a system and method for managing off-track retry. An implementation of a method of determining offset direction for read off-track retry includes storing analog to digital converter (ADC) values of data read from a data sector by a data reader in a read channel buffer, calculating an indicator value of the distribution of the ADC values, determining an amount of offset for the data reader based on the indicator value, and moving the data reader by the amount of offset before performing a read retry operation.
Abstract:
A heat-assisted magnetic recording device includes a write pole positionable adjacent a magnetic recording medium and configured to write data to the medium. A near-field transducer is situated proximate the write pole and configured to produce a thermal spot on the medium. A channel circuit is configured to generate a sequence of symbols having a length of nT, where T is a channel clock rate and n is an integer over a predetermined range. A write driver is configured to apply bi-directional write currents to the write pole to record the sequence of symbols at a location of the thermal spot on the medium, wherein a duration of applying the write currents to the write pole by the write driver is dependent on a length of the sequence of symbols and the effective thermal spot size.
Abstract:
A sequence of symbols is generated to describe a set of write data, the symbols having a length of nT, where T is a channel clock rate and n is an integer over a predetermined range. Bi-directional write currents are applied to a write pole to record the sequence of symbols to a magnetic storage medium. The write pole has an effective footprint with a downtrack length of mT, where m is an integer. The write currents are switched between a first rail current and a second rail current for alternating symbols, the write currents further transitioning to an intermediate current value for at least one channel clock period for symbols longer than 1T. Write currents are applied to the write pole when recording symbols having a length longer than mT using the effective footprint of the write pole as an interval.
Abstract:
In one implementation, this disclosure provides a method for executing a partial band rewrite operation comprising identifying a first track of a shingled data band to receive data of a write received at a shingled media storage device and writing a first subset of the received data to a media cache, where the first subset corresponds to the first track of the shingled data band to receive data of the write command. The method also includes writing a remaining subset of the received data to target locations within the shingled data band without updating data on the first track within the shingled data band corresponding to the first subset of the received data.
Abstract:
Embodiments described herein are operable with a storage device. In one embodiment, a method provides for buffering first portions of incoming sequential data from a plurality of channels in a buffer, and identifying locations of the storage device to store the first portions of the incoming sequential data. The method also provides for directly writing the first portions of the incoming sequential data from the buffer to the identified locations of the storage device.
Abstract:
Apparatus and method for data security in a data storage device. In some embodiments, an alternating pattern is written to a magnetic recording medium as a sequence of symbols at a selected clock rate. A repeatable magnetic signature is generated by reading the alternating pattern from the medium, the magnetic signature having relatively weak entropy at boundaries of the symbols. A multi-bit digital sequence is extracted from the repeatable magnetic signature, the digital sequence having relatively strong entropy. The digital sequence is stored in a separate memory coupled to the medium. Access to data stored on the medium is authenticated responsive to the digital sequence stored in the separate memory.
Abstract:
Systems and methods are disclosed for detecting shingled overwrite errors. When a read error is encountered when reading from shingled recording tracks, a processor may determine whether the read error is an error caused by shingled overwriting. The processor may determine whether the read error is caused by shingled overwriting by determining read signal quality of one or more sectors preceding the read error, such as based on a bit error count or bit error ratio (BER), and comparing the read signal quality to a threshold value. The processor may determine that the read error is caused by shingled overwriting when the read signal quality value is lower than the threshold.
Abstract:
A data sector is read using two or more passes of a read head over a recording medium. Each of the passes corresponds to a different cross-track offset, each of the data sectors being divided into two or more blocks. For each of the blocks, data is selected from one of the passes that read the block with a higher quality than other passes that read the block. The selected data from each of the blocks to is combined to form recovered data of the data sector.
Abstract:
An apparatus comprises a write pole for writing data to a magnetic recording medium and a near-field transducer (NFT) optically coupled to a laser source and configured to produce a thermal spot on the medium. A laser driver applies laser operation power (Iop) to the laser source. A channel circuit generates symbols having a length of nT, where T is a channel clock rate and n is an integer. The laser driver applies Iop to the laser source and a write driver applies bi-directional write currents to the write pole to record the symbols at a location of the thermal spot on the medium, wherein a duration of applying Iop to the laser source by the laser driver is dependent on a length of the symbols and the effective thermal spot size.