Patent ID: 7110203

Claim:
A magnetic disk drive including a combination type magnetic head having a writing head and a reading head, a magnetic disk medium facing the combination type magnetic head, a mechanism for moving the magnetic head to a predetermined position on the magnetic disk medium, an electronic circuit having the function of reading or writing information, and a temporary memory, the magnetic disk drive comprising the operations of: when data is to be written to the magnetic disk medium, adding, to the data, renewal information indicating a renewal frequency of data in a writing location and writing the renewal information and the data to the magnetic disk medium; storing the renewal information in the temporary memory; checking to see whether the renewal information added to the data written to the magnetic disk medium and the renewal information stored in the temporary memory accord, where the renewal information is added for verifying overwrite of the data; and when it is determined as a result of the checking that both the renewal information are the same, deleting the renewal information in the temporary memory and releasing an area retained by the renewal information in the temporary memory; and where the checking and deleting are executed during an idle state and a read operation.