Thermal recalibration is a process hard drives use to keep themselves operating smoothly as they heat up. Physical tolerances in a hard drive are extremely tight, and as the drive heats up and expands, its performance can suffer. Thermal recalibration allows the drive to correct for any expansion due to heat. Why should you care? Unfortunately, the drive momentarily stops reading or writing data while it is recalibrating – a big problem if you are using the drive for recording audio or video data! Many of the current crop of hard drives are intelligent enough to wait until they are idle before starting thermal recalibration.