One sign of the hard disk's calibration process is the spin-up and spin ?down events. The hard disk recalibrates itself to balance the changes in temperature which is also adjusting the position of data on the platter surface and when the hard disk can not scan the data properly. As a result, if the hard disk recalibrates a lot it might be a symptom of a failing hard disk.

However, take note that there is hard disk that programmed to saves power. In order to saves power the hard disk spin down and when there's work to be done that's the time to spin-up again.

Bad sectors of the hard disk will not cause by insufficient power of power cuts. The head actuators automatically park the heads on every occasion there is power cuts so that the platters won't crashed to head actuators. There is no way that power cuts will cause your hard disk bad sectors but having a bad power supply can fail your hard drive because it will surge the circuit board of it and may fry the motor.

A cheap power supplies do not kill hard drive even slowly killing it. That is a myth. Like any other power supply, when it send and surge the hard disk the disk will be instantly kill.

The truth is current design of hard disk's head actuators are not power-driven by any motor. Previous design of the head actuators are actually powered by a stepper motor. But currently head actuators use the voice coil instrument that uses electromagnetic power to stir the heads. In short, head actuators don't have a motor to fail and not powered by any mechanical motor.

In addition, take note that head actuators? automatically when there are power cuts meaning it is not an active process. Head actuator uses spring to park itself. The spring retracts the actuators when the power is cut while it moved against the spring tension when active.

There is a myth that bad sectors can be repaired once it was reformatted. A bad sector is an area where the hard disk cannot be written nor read properly. It may due to program-related problems that result in a logical bad sector. Bad sectors that are software related can be restores by formatting using any logical repair utility.

But in case the problem is due to eroded media or the hardware is directly damaged. Such physical bad sectors can no longer be repaired using any logical repair utility and formatting it will not restore them. Formatting them, however, can replace those bad sectors with spare sectors.

It is true that formatting will eliminate the bad sectors and will be replace with good sector on the spare section that part of every hard disk. But the performance will suffer because the heads will seek on the spare section in replacements of bad sectors. Bad sectors are signs of bad hard disk. Basically, it means that there something wrong with the hard disk. Bad sectors create debris on the platter and can cause to damage the hard drive.

Additionally, spare sectors are limited on any hard drive. Then once the hard disk runs out of spare sectors, formatting can not replace those bad sectors.