An air pump for generating air pressure in a hard disk drive (HDD) including a rotor disposed inside the HDD. The rotor comprises a first air pressure generating feature. The air pump further includes a stator. The stator includes a second air pressure generating feature. The first air pressure generating feature corresponds with the second air pressure generating feature and the air pressure is generated at a location where the first air pressure generating feature rotates in proximity to the second air pressure generating feature.