Magnetic disk device configured to specify a range of previously written track that is to be overlapped during a write and verify data previously written in the specified range after the write

A control method of a magnetic disk device, the method comprising:

• writing to a first area of a magnetic disk of the magnetic disk device in a manner such that a newly written track partially overlaps a previously written adjacent track, wherein writing first data to a first track that partially overlaps a second track includes:
• a first operation of specifying a range of the second track, which is to be overlapped as a result of writing the first data to the first track;
• a second operation of writing second data written in the specified range of the second track to a saving area;
• a third operation of writing the first data in the first track after the second operation;
• and
• a fourth operation of verifying the second data in the second track after the third operation.