Hard disk drives are nice, and they seem to last forever. Mean time between failure is 230,000 hours. Which seems a life time. New drives are very fast with improved spindle speeds(15.000 RPM). The bearings(air) do wear out(in blades), unless you install the drives horizontally. The magnetic surface has been improved some time ago by a surface coating which prevents heads from scraping and wear it out. The heads now use GMR(giant magntic resonance) to read sensitive(weak) magnetic fields. The coils to write the perpenticular magnetic fields use several bias frequencies for different depth. So Prml data compression keeps on increasing the magnetic density per square inch. This is expected to improve(60%) each and every year.

There is a problem if your power switvh can arc and put a magnetic signal on some part of the hdd. Often next to the end of your stored data. And you have to partition the damaged area out, if you can not restore data by scandisk. After you partirion the bad sectors out, you do not have to format it(bad sectors), but you have two logical drives now instead of one lengthy hdd. The first partition now may be insufficient for your operating system.

Another way is to partition to 90+% of the hdd, Then format it(one partition). The last data free part of the hdd will be used by format to substitute for the bad sectors. You lose some capacity, but the drive appears to be contiguous.

This leads to the important understanding of partitions in the MBR sector at zero track, zero sector. Before MBR has any data, the drive can not be seen by the operating system. You partition the hdd by fdisk, so that hdd drive number can be assigned by the bios. However, the bios can read the label(name, tracks and sectors and heads) of the hdd when you boot. If your bios can no longer see the label, you hdd is defective.

Once, you understand fdisk, then you understand grub or lilo which extends the MBR space in a file in the Linux operating system to boot more than one operating system.

Ah, the mystery of partitioning in hdd?