Hardware Reference
In-Depth Information
High-level formatting is not really a physical formatting of the drive (except with floppy
disks in some cases), but rather the creation of a table of contents for the disk. True low-
level formats of modern hard drives are performed by the manufacturer and technically
cannot be performed by the end user. Most hard drive manufacturers make initialization
and test programs available, which are the modern substitute for low-level format pro-
grams. Although the initialization programs do not technically re-create the sector header
or trailer marks, they do rewrite the data portion of all sectors as well as manage defects,
including the ability to reassign spare sectors to replace defective sectors. Normally, the
only time you run an initialization program is when you are attempting to repair a format
that has become damaged (parts of the disk become unreadable) or in some cases when
you want to wipe away all data on the drive.
Caution
In Windows XP and earlier, a high-level format does not overwrite the data area of the disk.
Instead, it only rewrites the table of contents, leaving the data area sectors intact. This is true
whetheryouusethe“quick”orfull-formatoptions.Assuch,uneraseutilities suchasRecuva
(
www.recuva.com
)
can recover files from a formatted drive because the data sectors are not
actually overwritten. However, this behavior was changed for Windows Vista and later, such
thatthestandardfullformatdoesoverwriteallthesectordatawithzeros,therebymakingthe
recovery ofanyprevious files ordata impossible. Youcan prevent the overwriting ofall data
sectors in Vista and later by using the “quick” format option. See the Microsoft KB941961
article at
http://support.microsoft.com
for more information.
Basic HDD Components
Many types of HDDs are on the market, but nearly all share the same basic physical com-
ponents. Some differences might exist in the implementation of these components (and in
thequalityofthematerialsusedtomakethem),buttheoperationalcharacteristics ofmost
drivesaresimilar.ThebasiccomponentsofatypicalHDDareasfollows(see
Figure9.9
):
Figure 9.9
Typical HDD components.
