Magnetic disk device and method of recording data

A method of recording data to be executed in a magnetic disk device, wherein

• the magnetic disk device is connected to a host,
• the host includes an input/output scheduler that groups command requests by any units, the input/output scheduler operates in one of a first scheduler switching system and a second scheduler switching system, switching being performed by a certain time for a command group including a plurality of write command requests in the first scheduler switching system, switching being performed by a certain number of bytes for the command group in the second scheduler switching system,
• the magnetic disk device:
• includes a plurality of tracks and includes a plurality of data sectors on each of the plurality of tracks;
• operating in response to command requests of read and write on the plurality of data sectors of the magnetic disk;
• and
• performing control at a time of performing read and write on the plurality of data sectors with a magnetic head in response to command requests when receiving, from the host, a command pattern that includes a plurality of command groups and in which the plurality of command groups are switched at certain timing, and
• the method comprising:
• recording any number of command requests while processing a command request that has been received;
• determining a transfer rate from a command request that has been recorded, to record the transfer rate;
• and
• comparing the transfer rate that has been determined with a reference transfer rate, to determine whether the input/output scheduler operates in the first scheduler switching system or in the second scheduler switching system based on a comparison result.