After low-level formatting is complete, we have a disk with tracks and sectors--but
nothing written on them. High-level formatting is the process of writing the file
system structures on the disk that let the disk be used for storing programs and data. If
you are using DOS, for example, the DOS FORMAT command
performs this work, writing such structures as the master boot record and file allocation
tables to the disk. High-level formatting is done after the hard disk has been partitioned, even if only one partition is to be used. See
here for a full description of DOS structures, also used
for Windows 3.x and Windows 9x systems.
The distinction between high-level formatting and low-level formatting is important. It
is not necessary to low-level format a disk to erase it: a high-level format will suffice
for most purposes; by wiping out the control structures and writing new ones, the old
information is lost and the disk appears as new. (Much of the old data is still on the
disk, but the access paths to it have been wiped out.) Under some circumstances a
high-level format won't fix problems with the hard disk and a zero-fill utility may be necessary.
Different operating systems use different high-level format programs, because they use
different file systems. However, the low-level format, which is the real place where
tracks and sectors are recorded, is the same.
Next: Defect Mapping and Spare Sectoring
