<s>
A	O
bad	B-Device
sector	I-Device
in	O
computing	O
is	O
a	O
disk	B-Application
sector	I-Application
on	O
a	O
disk	B-Device
storage	I-Device
unit	O
that	O
is	O
permanently	O
damaged	O
.	O
</s>
<s>
When	O
a	O
bad	B-Device
sector	I-Device
is	O
found	O
and	O
marked	O
,	O
the	O
operating	B-General_Concept
system	I-General_Concept
like	O
Windows	O
or	O
Linux	B-Application
will	O
skip	O
it	O
in	O
the	O
future	O
.	O
</s>
<s>
A	O
bad	B-Device
sector	I-Device
is	O
the	O
result	O
of	O
mechanical	O
damage	O
,	O
most	O
commonly	O
caused	O
by	O
a	O
head	O
crash	O
,	O
manufacturing	O
flaw(s )	O
,	O
wear-and-tear	O
,	O
physical	O
shock	O
,	O
sudden	O
power	O
outages	O
,	O
or	O
dust	O
intrusion	O
.	O
</s>
<s>
Bad	B-Device
sectors	I-Device
are	O
a	O
threat	O
to	O
information	O
security	O
in	O
the	O
sense	O
of	O
data	O
remanence	O
.	O
</s>
<s>
Bad	B-Device
sectors	I-Device
may	O
be	O
detected	O
by	O
the	O
operating	B-General_Concept
system	I-General_Concept
or	O
the	O
disk	B-Device
controller	O
.	O
</s>
<s>
Most	O
file	B-Application
systems	I-Application
contain	O
provisions	O
for	O
sectors	O
to	O
be	O
marked	O
as	O
bad	O
,	O
so	O
that	O
the	O
operating	B-General_Concept
system	I-General_Concept
avoids	O
them	O
in	O
the	O
future	O
.	O
</s>
<s>
Disk	B-Device
diagnostic	O
utilities	B-Application
,	O
such	O
as	O
CHKDSK	B-Device
(	O
Microsoft	B-Application
Windows	I-Application
)	O
,	O
Disk	B-Application
Utility	I-Application
(	O
on	O
macOS	B-Application
)	O
,	O
or	O
badblocks	B-Device
(	O
on	O
Linux	B-Application
)	O
can	O
actively	O
look	O
for	O
bad	B-Device
sectors	I-Device
upon	O
user	O
request	O
.	O
</s>
<s>
When	O
a	O
sector	O
is	O
found	O
to	O
be	O
bad	O
or	O
unstable	O
by	O
the	O
firmware	O
of	O
a	O
disk	B-Device
controller	O
,	O
the	O
disk	B-Device
controller	O
remaps	O
the	O
logical	O
sector	O
to	O
a	O
different	O
physical	O
sector	O
.	O
</s>
<s>
In	O
the	O
normal	O
operation	O
of	O
a	O
hard	O
drive	O
,	O
the	O
detection	O
and	O
remapping	O
of	O
bad	B-Device
sectors	I-Device
should	O
take	O
place	O
in	O
a	O
manner	O
transparent	O
to	O
the	O
rest	O
of	O
the	O
system	O
and	O
in	O
advance	O
before	O
data	O
is	O
lost	O
.	O
</s>
<s>
There	O
are	O
two	O
types	O
of	O
remapping	O
by	O
disk	B-Device
hardware	O
:	O
P-LIST	O
(	O
mapping	O
during	O
factory	O
production	O
tests	O
)	O
and	O
G-LIST	O
(	O
mapping	O
during	O
consumer	O
usage	O
by	O
disk	B-Device
microcode	O
)	O
.	O
</s>
<s>
Utilities	B-Application
can	O
read	O
the	O
Self-Monitoring	O
,	O
Analysis	O
,	O
and	O
Reporting	O
Technology	O
(	O
SMART	O
)	O
information	O
to	O
tell	O
how	O
many	O
sectors	O
have	O
been	O
reallocated	O
,	O
and	O
how	O
many	O
spare	O
sectors	O
the	O
drive	O
may	O
still	O
have	O
.	O
</s>
<s>
The	O
Windows	O
program	O
ATATool	O
can	O
be	O
used	O
to	O
create	O
deliberate	O
bad	B-Device
sectors	I-Device
by	O
manipulating	O
the	O
sector	O
Error	B-Error_Name
correction	I-Error_Name
code	I-Error_Name
(	O
ECC	O
)	O
data	O
.	O
</s>
<s>
This	O
can	O
be	O
used	O
to	O
verify	O
bad	B-Device
sector	I-Device
support	O
in	O
disk	B-Application
utilities	I-Application
and	O
forensic	O
tools	O
.	O
</s>
