Magnetic disk device configured to write parity data that is based on data being written to a parity sector when no error is detected in writing the data being written

A magnetic disk device comprising:

• a magnetic disk that includes a plurality of tracks on which data are written to and read from;
• and
• a controller configured to
• receive write data to be written to a first sector of a track in the plurality of tracks,
• generate a first data string based on the write data and on a logical identifier for the first sector,
• attempt to cause the first data string to be written to the first sector,
• determine whether a write error has occurred while the first data string is written to the first sector,
• generate a second data string based at least in part on the first data string, and
• in response to determining that no write error has occurred while the first data string is written to the first sector, cause a parity data string that is based at least in part on the second data string to be written to a second sector of the track that stores parity data for the track.