A configuration is realized in which a packet delimiter can be discriminated from an MMTP packet string including MMT format data, and a packet can be selectively acquired and reproduced. The MMT format data is input through a broadcast wave or the like, a packet length of an MMT protocol (MMTP) packet including the MMT format data is acquired, and recording data in which an additional header storing the acquired packet length is set before the MMTP packet, is generated, and is recorded in an information recording medium. A reproducing device is capable of discriminating a delimiter of each MMTP packet, according to the packet length of the MMTP packet, read from the additional header, is capable of acquiring reproducing data, for example, image data, from the selected packet, and is capable of decoding and reproducing the acquired data.

A virtual file system (VFS) is constructed by reliably acquiring subsequent data corresponding to an information recording medium from a local storage unit, and thus, data reproduction is executed. A data processing unit executes processing of selecting data associated with the information recording medium from the local storage unit, as reproduction target data, executes directory name calculation processing in which a conversion function corresponding to a version of the information recording medium is applied to configuration data of a root certificate recorded in the information recording medium, at the time of performing the processing of selecting the reproduction target data, and selects data which is recorded in a directory having a calculated directory name from the local storage unit, as the reproduction target data.

According to one embodiment, a magnetic disk device includes heads and a controller. The heads write data in a recording region of the magnetic disk. The controller divides in order, by a track group with a constant size, an entire region of the recording region where management regions indicating physical positions corresponding to the heads, respectively, creates the track groups so as to straddle the management regions at boundaries of the management regions, and controls writing of the data for each of the track groups. The controller assigns unique and logically consecutive numbers to the track groups and manages information on the management regions to which the track groups belong.

According to one embodiment, a magnetic disk device includes a disk including a first region and a second region different from the first region, a head that writes data on the disk and reads data from the disk, an actuator that positions the head on the disk, and a controller which positions the head by driving the actuator and writes data in the first region and the second region with the head, a skew angle of the head with respect to a circumferential direction of the disk varying within a first angle in the first region, and varying, in the second region, from a second angle larger than the first angle to a third angle larger than the first angle and the second angle.

According to one embodiment, a magnetic disk device including a disk, a head, and a controller which sets a first track pitch based on fringing when a second track is written, sets a second track pitch based on fringing when a third track is written, calculates a difference between the first track pitch and the second track pitch, sets, when the difference is less than or equal to a reference value, an area to which the first track is written in a first recording area, and sets, when the difference is greater than the reference value, the area to which the first track is written in a second recording area.

An apparatus according to one approach includes a module having an array of transducers having at least two transducers. The apparatus also includes a persistent memory having stored therein data of a span of the array of transducers at a particular temperature. An apparatus according to another approach includes a module having fiducials at known positions relative to an array of transducers. The apparatus also includes a persistent memory having stored therein data of a span between the fiducials at a particular temperature. The fiducial span may be used in conjunction with the known locations of the fiducials relative to the array to characterize the span of the array.

In a multilayer optical disc having information layers conforming to a plurality of different optical disc standards, because the type of each information layer is not recorded in the other information layers, in read and write operations by a compatible optical disc device conforming to a plurality of optical disc standards, every time the information layer being accessed changes, it has been necessary to read the type of the information layer and select a method of generating a tracking error signal adapted to the type of information layer, so access has taken time. In order to solve the above problem, in the optical multilayer disc according to the present invention, having information layers conforming to a plurality of different optical disc standards, in an area in one of the information layers, information about the other information layers is recorded. The time required to access the other information layers can be reduced by using this information to select a tracking error signal generating method.

According to one embodiment, a magnetic disk device includes a disk medium which has a first region, a second region, and a redundant third region, and a control circuitry. The first region is a region to which first data received from a host is written. The second region is a region to which the first data is temporarily written before the first data is written to the first region. The control circuitry executes defect detection to the first region. Upon detecting a defect, the control circuitry substitutes a first location having the defect in the first region with a second location in the third region. Depending on a total size of free regions of the third region, the control circuitry reallocates a fourth region from the second region to the third region. The fourth region is part or all of the second region.

An optical disk (100) of the present invention includes (i) a medium information region (101) (a) in which type identification information is recorded by recesses and/or protrusions which are formed by a given modulation method and whose lengths are longer than a length of an optical system resolution limit of a playback device and (b) in which first address information is recorded in a first address data format and (ii) a data region (102) (a) in which content data is recorded by recesses and/or protrusions which are formed by the given modulation method and which include a recess and/or a protrusion whose length is shorter than the length of the optical system resolution limit and (b) in which second address information is recorded in a second address data format.

A computer program product, according to one embodiment, includes a computer readable storage medium having program instructions embodied therewith. The program instructions are readable and/or executable by a processor to cause the processor to: receive a first portion of data, and divide the first portion of data into a plurality of blocks. An identification segment having identification information therein is appended to each of the blocks, each block and the corresponding identification information appended thereto forming a record. Each record is written in a data partition of the magnetic tape, and an index may be written in the data partition of the magnetic tape. The magnetic tape is rewound to a beginning of tape in response to a final one of the records being written in the magnetic tape, and the index is written in an index partition of the magnetic tape.