A Note on Formatting of Disks

Earlier disks were needed to be checked and formatted for bad blocks. A procedure of formatting entailed writing the track, head and sector in a sector preamble and a checksum in the post amble to each sector on the disk.

At the similar time, sectors which were unusable due to flaws in the disk surface were marked and depending on the category of disk, an instead sector mapped into its place.

But now-a-days both the IDE and SCSI disks are pre-formatted from the factory. However, they transparently handle bad blocks on the disk and remap them without much assistance from the operating system.