when a hot start, the rotor and the cylinder metal temperature is higher, if evacuated, cold air will into the cylinder along the seal, and the cold air is flowing under the cylinder, therefore, a sharp decline at the cylinder temperature, increasing the difference temperature between the upper and lower cylinder, cylinder deformation, static and dynamic friction, serious when the disk drive is not properly invested, resulting in large shaft bending, so the hot start should be do bearing seal first before evacuate the vaccum.