A data object has a lock and a condition indicator associated with it. Based at least partly on detecting a first setting of the condition indicator, a reader stores an indication that the reader has obtained read access to the data object in an element of a readers structure and reads the data object without acquiring the lock. A writer detects the first setting and replaces it with a second setting, indicating that the lock is to be acquired by readers before reading the data object. Prior to performing a write on the data object, the writer verifies that one or more elements of the readers structure have been cleared.

According to one embodiment, a magnetic disk device includes a disk including two first servo sectors and at least a second servo sector, a head, and a controller, wherein the first servo sector includes burst data and a first data pattern written before the circumferential direction of the burst data, the second servo sector includes the burst data, the first data pattern, and a second data pattern written after the circumferential direction of the burst data, a first frequency of the first data pattern is different from a second frequency of the second data pattern, and a first length of the first data pattern is different from a second length of the second data pattern.

The present disclosure provides an optical disk device capable of reproducing data recorded on a high linear density optical disk stably. The optical disk device according to the disclosure is characterized by being equipped with a recording expected waveform generation circuit which generates, at the time of recording, an expected waveform that is expected to be obtained at the time of decoding; and a recording pulse generation circuit which generates a recording pulse for driving a laser with power and a time width suitable for an amplitude value of the recording expected waveform for each sampling point of the recording expected waveform.

According to an embodiment, a magnetic disk has a plurality of second servo sectors and a plurality of third servo sectors each arranged between two second servo sectors of the plurality of second servo sectors, in which the second and third servo sectors are arranged in a circumferential direction. A controller performs a first demodulation for detecting a servo mark and demodulating a burst pattern on the servo data in each second servo sector. The controller performs a second demodulation for demodulating the burst pattern without detecting the servo mark, on the servo data in each third servo sector. The controller performs the second demodulation on the servo data in a fourth servo sector which is one of the plurality of second servo sectors in a case where the detection of the servo mark fails when the first demodulation is performed on the servo data in the fourth servo sector.

The present disclosure provides an optical disk device capable of reproducing data recorded on a high linear density optical disk stably. The optical disk device according to the disclosure is characterized by being equipped with a recording expected waveform generation circuit which generates, at the time of recording, an expected waveform that is expected to be obtained at the time of decoding; and a recording pulse generation circuit which generates a recording pulse for driving a laser with power and a time width suitable for an amplitude value of the recording expected waveform for each sampling point of the recording expected waveform.

According to one embodiment, a magnetic disk device includes a disk including two first servo sectors and at least a second servo sector, a head, and a controller, wherein the first servo sector includes burst data and a first data pattern written before the circumferential direction of the burst data, the second servo sector includes the burst data, the first data pattern, and a second data pattern written after the circumferential direction of the burst data, a first frequency of the first data pattern is different from a second frequency of the second data pattern, and a first length of the first data pattern is different from a second length of the second data pattern.

According to one embodiment, a magnetic disk device includes a disk including two first servo sectors and at least a second servo sector, a head, and a controller, wherein the first servo sector includes burst data and a first data pattern written before the circumferential direction of the burst data, the second servo sector includes the burst data, the first data pattern, and a second data pattern written after the circumferential direction of the burst data, a first frequency of the first data pattern is different from a second frequency of the second data pattern, and a first length of the first data pattern is different from a second length of the second data pattern.

A drive substrate for a camera and a broadcast camera which are free from the occurrence of bit errors in video over a low to high temperature range while achieving reduction in a production cost and development time are provided. The phase of a clock is appropriately adjusted by repeating the processes of shifting the clock phase in a first period within a blanking period during which effective pixel data of each frame in a video signal is not used, detecting the occurrence/non-occurrence of a bit error based on the phase-shifted clock in a second period within the blanking period, and further shifting the clock phase in a third period within the blanking period.

A drive substrate for a camera and a broadcast camera which are free from the occurrence of bit errors in video over a low to high temperature range while achieving reduction in a production cost and development time are provided. The phase of a clock is appropriately adjusted by repeating the processes of shifting the clock phase in a first period within a blanking period during which effective pixel data of each frame in a video signal is not used, detecting the occurrence/non-occurrence of a bit error based on the phase-shifted clock in a second period within the blanking period, and further shifting the clock phase in a third period within the blanking period.

An erasure code-based partial write-in method and apparatus are provided. According to the method, a data node receives a first updating request carrying updating data and first version information from a client, wherein the first version information is information stored by the client and indicating a version of a target data block to be updated with the updating data, a data amount of the updating data is less than a data amount of one erasure code group which comprises m data blocks and k check data blocks, both m and k being natural numbers; the data node acquires second version information in response to the first updating request, wherein the second version information is information stored in the node and indicating the version of the target data block; the data node processes the updating data according to a matching result of the first version information and second version information.