Abstract: According to one embodiment, a magnetic disk apparatus is provided with a magnetic disk, a buffer memory, and a control circuit. The magnetic disk has plural bands, each of which is a storage area in which data is written by the method of SMR. The control circuit receives a read request from outside. If the data requested to be read is first data of an update target stored in a first band among plural bands, the control circuit reads the first data from the first band, stores the first data in a buffer memory, and updates the first data in the buffer memory. Then, the control circuit transmits the first data in the buffer memory to the outside and writes the first data in the buffer memory to one of the plural bands.

Abstract: According to an embodiment, each of a plurality of controller chips included in a magnetic disk device includes a buffer control circuit and an arbitration circuit, and controls a corresponding one of a plurality of actuator systems. The first controller chip is connected to a buffer memory via the buffer control circuit included in the first controller chip, and is connected to the second controller chip. The second controller chip is connected to the first controller chip and the third controller chip. The arbitration circuit included in the second controller chip performs arbitration between data transfer between the third controller chip and the first controller chip and data transfer between the first controller chip and an actuator system controlled by the second controller chip among the plurality of actuator systems.

Abstract: An electrostatic chuck includes a plurality of ceramic substrates each having a step formed at a peripheral edge portion of one surface, the ceramic substrates being arranged adjacent to each other so that the steps face each other, electrodes each embedded in each of the plurality of ceramic substrates, and a filling portion that fills a groove portion formed by the facing steps of the adjacent ceramic substrates.

Abstract: According to one embodiment, a magnetic disk device incudes a first magnetic disk, a first actuator that reads/writes data from/to the first magnetic disk, a first controller that controls the first actuator, a second magnetic disk, a second actuator that reads/writes data from/to the second magnetic disk, a second controller that controls the second actuator, wherein the first controller executes read/write processing, and the second controller stores trace data of the read/write processing when the first controller executes the read/write processing.

Abstract: According to an embodiment, each of a plurality of controller chips included in a magnetic disk device includes a buffer control circuit and an arbitration circuit, and controls a corresponding one of a plurality of actuator systems. The first controller chip is connected to a buffer memory via the buffer control circuit included in the first controller chip, and is connected to the second controller chip. The second controller chip is connected to the first controller chip and the third controller chip. The arbitration circuit included in the second controller chip performs arbitration between data transfer between the third controller chip and the first controller chip and data transfer between the first controller chip and an actuator system controlled by the second controller chip among the plurality of actuator systems.

Abstract: According to one embodiment, a magnetic disk apparatus is provided with a magnetic disk, a buffer memory, and a control circuit. The magnetic disk has plural bands, each of which is a storage area in which data is written by the method of SMR. The control circuit receives a read request from outside. If the data requested to be read is first data of an update target stored in a first band among plural bands, the control circuit reads the first data from the first band, stores the first data in a buffer memory, and updates the first data in the buffer memory. Then, the control circuit transmits the first data in the buffer memory to the outside and writes the first data in the buffer memory to one of the plural bands.

Abstract: According to one embodiment, a magnetic disk device incudes a first magnetic disk, a first actuator that reads/writes data from/to the first magnetic disk, a first controller that controls the first actuator, a second magnetic disk, a second actuator that reads/writes data from/to the second magnetic disk, a second controller that controls the second actuator, wherein the first controller executes read/write processing, and the second controller stores trace data of the read/write processing when the first controller executes the read/write processing.

Abstract: An electrostatic chuck includes a plurality of ceramic substrates each having a step formed at a peripheral edge portion of one surface, the ceramic substrates being arranged adjacent to each other so that the steps face each other, electrodes each embedded in each of the plurality of ceramic substrates, and a filling portion that fills a groove portion formed by the facing steps of the adjacent ceramic substrates.

Abstract: According to one embodiment, a magnetic disk device includes a magnetic disk, an actuator, a nonvolatile memory, and a controller. When a first determination condition of whether a total value of an amount of data for which execution completion has not been notified in one processing thread that executes a write command, the data having not been written to the magnetic disk, and an amount of the data for which execution completion has been notified in another processing thread that executes the write command, the data having not been written to the magnetic disk, is less than or equal to a capacity of the nonvolatile memory holds, the controller notifies the host of execution completion of the write command in the one processing thread.

Abstract: According to one embodiment, a magnetic disk device includes a magnetic disk, a first magnetic head and a second magnetic head that are moved independently of each other, a first controller chip, a second controller chip, and a third memory. The first controller chip includes a first processor and a first memory, and controls the first magnetic head. The second controller chip includes a second processor and a second memory, and controls the second magnetic head. Management information is stored in the third memory. The first controller chip is connected to the third memory. The second controller chip is connected to the third memory via the first controller chip. The second controller chip saves the management information into the second memory.

Abstract: According to one embodiment, a magnetic disk device includes a magnetic disk, a first magnetic head and a second magnetic head that are moved independently of each other, a first controller chip, a second controller chip, and a third memory. The first controller chip includes a first processor and a first memory, and controls the first magnetic head. The second controller chip includes a second processor and a second memory, and controls the second magnetic head. Management information is stored in the third memory. The first controller chip is connected to the third memory. The second controller chip is connected to the third memory via the first controller chip. The second controller chip saves the management information into the second memory.

Abstract: According to one embodiment, a magnetic disk device including a disk, a head which reads data from the disk, a memory which records data, and a controller which includes a table, and records, at a first time point at which a read gate is open, a first area number of a first area of the table in which first information related to first data is recorded, a first serial number of the first data added when the read gate is open, and a first count value of the first data, in the first area.

Abstract: An electrostatic chuck includes a base member and an electrostatic chuck substrate. The base member includes a cooling path. The electrostatic chuck substrate is connected to an upper surface of the base member through an adhesive layer so as to attract a substrate to be mounted. The cooling path includes an introduction portion, a discharge portion and a conduit. The cooling medium is introduced from an outside of the base member to the introduction portion. The cooling medium is discharged from the discharge portion. The conduit includes a start end portion communicating with the introduction portion and a final end portion communicating with the discharge portion. The introduction portion is inclined toward a lower surface of the base member and at a predetermined angle with respect to an axis perpendicular to the upper surface. The introduction portion extends from the lower surface toward the start end portion.

Abstract: A magnetic disk apparatus includes a disk and a controller. The disk includes a plurality of tracks including a first track and a second track that is different from the first track. A plurality of data sectors are located on the tracks. The data sectors include short data sectors and long data sectors, each including a plurality of short data sectors. If the controller accesses a long data sector located at an end of the first track, the controller first accesses a short data sector of the long data sector at the end of the first track, and then accesses a short data sector of the long data sector at the beginning of the second track.

Abstract: According to one embodiment, a storage device includes a storage medium configured to store second data groups including first data groups, each of the first data groups including user data encrypted with a common encryption key and first information concerned with the encryption key, and a controller configured to hold second information regarding a latest encryption key, read one of the first data groups included in one of the second data groups, compare the second information and the first information acquired from the one of the first data groups, and stop a read operation of reading the first data groups included in the second data groups upon the first information being different from the second information.

Abstract: An electrostatic chuck includes a base member and an electrostatic chuck substrate. The base member includes a cooling path. The electrostatic chuck substrate is connected to an upper surface of the base member through an adhesive layer so as to attract a substrate to be mounted. The cooling path includes an introduction portion, a discharge portion and a conduit. The cooling medium is introduced from an outside of the base member to the introduction portion. The cooling medium is discharged from the discharge portion. The conduit includes a start end portion communicating with the introduction portion and a final end portion communicating with the discharge portion. The introduction portion is inclined toward a lower surface of the base member and at a predetermined angle with respect to an axis perpendicular to the upper surface. The introduction portion extends from the lower surface toward the start end portion.

Abstract: A magnetic disk apparatus includes a disk and a controller. The disk includes a plurality of tracks including a first track and a second track that is different from the first track. A plurality of data sectors are located on the tracks. The data sectors include short data sectors and long data sectors, each including a plurality of short data sectors. If the controller accesses a long data sector located at an end of the first track, the controller first accesses a short data sector of the long data sector at the end of the first track, and then accesses a short data sector of the long data sector at the beginning of the second track.

Abstract: A layered body having a single crystal layer including a group III nitride having a composition AlxGayInzN (wherein, X, Y and Z are rational numbers respectively satisfying 0.9?X?1.0, 0.0?Y?0.1, 0.0?Z?0.1, and X+Y+Z=1.0) on a sapphire substrate. The layered body includes an initial single crystal layer that includes the group III nitride composition, an oxygen concentration of 1×1020 cm?3 or more and 5×1021 cm?3 or less and a thickness of 15 nm or more and 40 nm or less on the sapphire substrate and a second group III nitride single crystal layer including the group III nitride composition and having a reduced oxygen concentration than the initial single crystal layer.

Abstract: According to one embodiment, a magnetic disk apparatus includes an RW channel with an internal memory for processing data to be read/written from/to a magnetic disk, a transfer controller for controlling data transfer between a host apparatus and the RW channel, and a processor for controlling the RW channel and transfer controller. The processor reads, from the magnetic disk, predetermined area data including to-be-rewritten data, subjects the read predetermined area data to error correction processing in the RW channel, and stores resultant data in the internal memory. The processor rewrites, with rewrite data from the host apparatus, the to-be-rewritten data of the predetermined area data stored in the internal memory to update the predetermined area data, adds an error correction code to the updated data in the RW channel module, and writes resultant data to the magnetic disk.

Abstract: According to one embodiment, a magnetic disk apparatus includes an RW channel with an internal memory for processing data to be read/written from/to a magnetic disk, a transfer controller for controlling data transfer between a host apparatus and the RW channel, and a processor for controlling the RW channel and transfer controller. The processor reads, from the magnetic disk, predetermined area data including to-be-rewritten data, subjects the read predetermined area data to error correction processing in the RW channel, and stores resultant data in the internal memory. The processor rewrites, with rewrite data from the host apparatus, the to-be-rewritten data of the predetermined area data stored in the internal memory to update the predetermined area data, adds an error correction code to the updated data in the RW channel module, and writes resultant data to the magnetic disk.