A method of determining a size of an error generated in a servo sector, a write control method of controlling whether to write data to data sectors successive to a servo sector according to the size of the error generated in the servo sector therein, a HDD using the write control method, and a recording media storing computer programs for executing the methods. A method of determining a size of an error generated in a servo sector of a HDD includes: reading servo information from the servo sector in which the error was generated; and determining the size of the error by the number of corresponding bits that differ from each other between the read servo information and a normal servo information.