Magnetic disk drive and method for controlling microactuator in magnetic disk drive

A method for controlling a first microactuator and a second microactuator in a magnetic disk drive, the first microactuator configured to allow a first head to make micromotion based on a first operation amount, the first head associated with a first surface of a disk, the second microactuator being configured to allow a second head to make micromotion based on a second operation amount, the second head associated with a second surface of the disk, wherein the method comprises:

• generating the first operation amount to be provided to the first microactuator when the first surface is used as a tracking surface;
• providing the first operation amount to the first microactuator;
• and
• providing the second operation amount to the second microactuator, the second operation amount obtained by inverting a polarity of a first frequency component contained in the first operation inverting polarities of frequency components other than the first frequency component.

A magnetic disk drive comprising:

• a disk comprising a first surface and a second surface;
• a first microactuator configured to allow a first head to make micromotion based on a first operation amount, the first head associated with the first surface;
• a second microactuator configured to allow a second head to make micromotion based on a second operation amount, the second head associated with the second surface;
• and
• a servo controller configured to provide the first operation amount to the first microactuator and to provide the second operation amount to the second microactuator, the second operation amount obtained by inverting a polarity of a first frequency component contained in the first operation amount and resulting from disk flutter, and by not inverting polarities of frequency components other than the first frequency component if the first operation amount is generated when the first surface is used as a tracking surface.