Heat dissipation is tied directly to power consumption, and as drives age, disk failure rates increase at higher drive temperatures.
Techniques Used For Heat Dissipation:
 Smaller form factor drives often use less power hence less heat is generated.
 Actively controlling the seek speed so that the head arrives at its destination only just in time to read the sector, rather than arriving as quickly as possible and then having to wait for the sector to come around.
 Hard drive companies are now producing Green Drives that require much less power and cooling. They spin slower than 5,400 rpm thereby generating less heat.
 Power consumption can also be reduced by parking the drive heads when the disk is not in use reducing friction, adjusting spin speeds, and disabling internal components when not in use.