According to one embodiment, a magnetic disk device includes a disk, a head configured to write data to the disk and read data from the disk, and a controller configured to write position information of the head when writing a first track of the disk and a second track partially overlapping with the first track in a first region of the first track at which read processing on the first track is started.

The disclosed technology includes methods and systems that reduce off-track write retry operations in shingled magnetic recording systems. In one implementation, the method includes writing data to an initial track, determining which side of the initial track is a shingled side, calculating a percentage of position error signal (PES) at a shingled side end of the initial track (PES1) when an off-track write operation occurs, determining whether the PES1 meets a first pre-determined threshold, continue writing data to a second track responsive to determining the PES1 is below a first pre-determined threshold, calculating a percentage of PES at a shingled side end of the second track (PES2), determining whether a combined value of PES1 and PES2 is above a second predetermined threshold to determine a probability value of the initial track being erased, and continue writing to a third track if the combined value is below the second predetermined threshold.

The disclosed technology includes methods and systems that reduce off-track write retry operations in shingled magnetic recording systems. In one implementation, the method includes writing data to an initial track, determining which side of the initial track is a shingled side, calculating a percentage of position error signal (PES) at a shingled side end of the initial track (PES1) when an off-track write operation occurs, determining whether the PES1 meets a first pre-determined threshold, continue writing data to a second track responsive to determining the PES1 is below a first pre-determined threshold, calculating a percentage of PES at a shingled side end of the second track (PES2), determining whether a combined value of PES1 and PES2 is above a second predetermined threshold to determine a probability value of the initial track being erased, and continue writing to a third track if the combined value is below the second predetermined threshold.

A method for managing data bands within an interlaced magnetic recording (IMR) architecture includes transmitting read/write characteristics of a logical block address space, the read/write characteristics including coupling information characterizing a physical arrangement of data blocks associated with different logical zones in the logical block address space, where each of the logical zones spans a continuous range of logical block addresses mapped to a series of data blocks physically interlaced with another series of data blocks corresponding to another one of the logical zones. The method further provides for executing a write command instructing a data write to a target logical zone of the logical zones, the write command being generated based on the transmitted coupling information.

A first drive volume formed on a disk within a drive enclosure. The first drive volume is read from and written to by a first head that is moved by a first actuator, A second drive volume is formed on the one or more disks. The second volume is read from and written to by a second head that is moved via a second actuator within the drive enclosure. The second actuator is separate and independent from the first actuator. Data of the first drive volume is duplicated onto the second drive volume, Background validation operations are performed on the second drive volume instead of the first volume.

According to one embodiment, a magnetic disk device, includes a disk including a track including a plurality of servo sectors, a head including a write head which writes data to the disk and a plurality of read heads which read the data from the disk, and a controller configured to simultaneously acquire a plurality of pieces of correction data for repeatable runout of the disk by the read heads, acquire a first correction data and a second correction data based on the correction data, write the first correction data and the second correction data to the disk, and correct a position of the head based on the first correction data and the second correction data.

According to one embodiment, a magnetic disk device, includes a disk including a track including a plurality of servo sectors, a head including a write head which writes data to the disk and a plurality of read heads which read the data from the disk, and a controller configured to simultaneously acquire a plurality of pieces of correction data for repeatable runout of the disk by the read heads, acquire a first correction data and a second correction data based on the correction data, write the first correction data and the second correction data to the disk, and correct a position of the head based on the first correction data and the second correction data.

Data can be transmitted and represented by signal gaps in a transmission, the gaps having various attributes. In various examples, data points are encoded and represented by the attributes of said signal gaps. Various attributes of such gaps, including duration, pattern, quantity, time, and/or coordination with a gap in another signal can represent data.

Technologies are provided for using an index in one region of a storage device to track modifications to data stored in another region of the storage device. The index can be stored in a first storage region using a first storage format, and data items can be stored in a second storage region using a second storage format. The index can map logical identifiers for data items to locations in the second storage region where the data items are stored. Instead of modifying a data item in the second storage device region, an entry in the index can be updated to mark the data item as deleted. Requests for data items can be reconciled using the index before returning the requested data items. Storage locations in the second region that are associated with index entries that are marked as deleted can be reclaimed and used to store additional data items.

Methods and systems for detecting hidden sectors in a hard drive. The method may include initiating a linear copy of the hard drive and, while the hard drive is being copied, capturing images of a platter and an actuator arm within the hard drive using an imaging device. The captured images are output and they indicate a range of movement of the actuator arm across the platter during the linear copy. Ranges of movement that fail to scan across the full expected size of the platter may be indicative of a modified partition record that maliciously hides a portion of the hard drive from the copy operation.