According to one embodiment, a magnetic recording apparatus measures and stores recording signal quality of a disk at an initial stage, inspects the recording signal quality before data is recorded, determines whether or not the recording signal quality obtained in the inspection satisfies a standard when compared to the stored recording signal quality at the initial stage, adjusts, based on a result of the determination, light irradiation power of a light irradiation element so as to satisfy the standard, determines a read offset amount based on a result of the adjustment, and performs control so that a position of a read head is shifted based on the determined read offset amount.

The present disclosure describes aspects of constant-density writing for magnetic storage media. In some aspects, a constant-density writer delays transitions between bits within write data to enable constant-density writing. The write data has an initial bit period based on a constant clock signal, which is generated based on the rotation of a media disk. The constant-density writer modifies the write data to generate phase-delayed write data, which has a bit period that is greater than or equal to the initial bit period. To realize this bit period, the constant-density writer changes write phases of bit transitions within the write data. The constant-density writer can also insert stretch bits, filter single-bit transitions, and mitigate glitches within the phase-delayed write data.

According to one embodiment, a recording density setting method includes performing first process and performing second process. The first process including recording and reading data on and from a disk medium of a magnetic disk device, and acquiring first information for setting the read data to satisfy a certain quality criterion. The first information represents a first shape of a first plurality of unit regions. Each of the a first plurality of unit regions is a recording region of a unit capacity. The second process includes acquiring second information representing a second shape of the first plurality of unit regions, and setting a recording density on the basis of the second information. The second shape is formed by adding margin regions having the same area to the first plurality of unit regions of the first shape.

A system includes, according to one embodiment, a magnetic head having a plurality of write transducers configured to store data to tracks of a sequential access medium and a plurality of read transducers. Each read transducer is configured to read data from the sequential access medium after being written thereto by a corresponding write transducer. A first of the read transducers is aligned with a first of the write transducers, wherein the output of the first read transducer is produced during read-while-write. The system also includes a controller and logic integrated with and/or executable by the controller. The logic is configured to read, using the plurality of read transducers, encoded data from a plurality of tracks of the sequential access medium simultaneously. The logic is configured to determine that one or more tracks of the sequential access medium are dead within a sliding window and rewrite a set of encoded data from the one or more dead tracks to one or more live tracks in a rewrite area of the sequential access medium. Other systems, methods, and computer program products are described according to more embodiments.

According to one embodiment, a recording density setting method includes performing first process and performing second process. The first process including recording and reading data on and from a disk medium of a magnetic disk device, and acquiring first information for setting the read data to satisfy a certain quality criterion. The first information represents a first shape of a first plurality of unit regions. Each of the a first plurality of unit regions is a recording region of a unit capacity. The second process includes acquiring second information representing a second shape of the first plurality of unit regions, and setting a recording density on the basis of the second information. The second shape is formed by adding margin regions having the same area to the first plurality of unit regions of the first shape.

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.

A data memory system is described, where there may be an asymmetry in the time needed to write or erase data and the time needed to read data. The data may be stored using a RAID data storage arrangement and the reading, writing and erasing operations on the modules arranged such that the erasing and writing operations may be performed without significant latency for performing a read operation. Where a failure of a memory module in the memory system occurs, methods for recovering the data of the failed module are disclosed which may selected in accordance with policies that may relate to the minimizing the possibility of irretrievable data loss, or degradation of latency performance.

A data memory system is described, where there may be an asymmetry in the time needed to write or erase data and the time needed to read data. The data may be stored using a RAID data storage arrangement and the reading, writing and erasing operations on the modules arranged such that the erasing and writing operations may be performed without significant latency for performing a read operation. Where a failure of a memory module in the memory system occurs, methods for recovering the data of the failed module are disclosed which may selected in accordance with policies that may relate to the minimizing the possibility of irretrievable data loss, or degradation of latency performance.

A system includes, according to one embodiment, a magnetic head having a plurality of write transducers configured to store data to tracks of a sequential access medium and a plurality of read transducers. Each read transducer is configured to read data from the sequential access medium after being written thereto by a corresponding write transducer. A first of the read transducers is aligned with a first of the write transducers, wherein the output of the first read transducer is produced during read-while-write. The system also includes a controller and logic integrated with and/or executable by the controller. The logic is configured to read, using the plurality of read transducers, encoded data from a plurality of tracks of the sequential access medium simultaneously. The logic is configured to determine that one or more tracks of the sequential access medium are dead within a sliding window and rewrite a set of encoded data from the one or more dead tracks to one or more live tracks in a rewrite area of the sequential access medium. Other systems, methods, and computer program products are described according to more embodiments.

In one embodiment, a system includes a magnetic head having a plurality of write transducers and a plurality of read transducers. Each read transducer is configured to read data from a sequential access medium after being written thereto by a corresponding write transducer. The system also includes a controller and logic integrated with and/or executable by the controller. The logic is configured to read, using the plurality of read transducers, encoded data from a plurality of tracks of the sequential access medium simultaneously. The logic is also configured to determine that one or more tracks of the sequential access medium are dead within a sliding window. Moreover, the logic is configured to rewrite a set of encoded data from the one or more dead tracks to live tracks in a rewrite area of the sequential access medium. Other systems, methods, and computer program products are described according to more embodiments.