<s>
A	O
disk	B-Application
utility	I-Application
is	O
a	O
utility	B-Application
program	I-Application
that	O
allows	O
a	O
user	O
to	O
perform	O
various	O
functions	O
on	O
a	O
computer	B-Device
disk	I-Device
,	O
such	O
as	O
disk	B-Application
partitioning	I-Application
and	O
logical	B-Application
volume	I-Application
management	I-Application
,	O
as	O
well	O
as	O
multiple	O
smaller	O
tasks	O
such	O
as	O
changing	O
drive	O
letters	O
and	O
other	O
mount	O
points	O
,	O
renaming	O
volumes	O
,	O
disk	B-Device
checking	I-Device
,	O
and	O
disk	B-Application
formatting	I-Application
,	O
which	O
are	O
otherwise	O
handled	O
separately	O
by	O
multiple	O
other	O
built-in	O
commands	O
.	O
</s>
<s>
Each	O
operating	B-General_Concept
system	I-General_Concept
(	O
OS	O
)	O
has	O
its	O
own	O
basic	O
disk	B-Application
utility	I-Application
,	O
and	O
there	O
are	O
also	O
separate	O
programs	O
which	O
can	O
recognize	O
and	O
adjust	O
the	O
different	O
filesystems	B-Application
of	O
multiple	O
OSes	O
.	O
</s>
<s>
Disk	B-Application
cleaners	I-Application
are	O
computer	O
programs	O
that	O
find	O
and	O
delete	O
potentially	O
unnecessary	O
or	O
potentially	O
unwanted	O
files	B-Operating_System
from	O
a	O
computer	O
.	O
</s>
<s>
The	O
purpose	O
of	O
such	O
deletion	O
may	O
be	O
to	O
free	O
up	O
disk	B-Device
space	O
,	O
to	O
eliminate	O
clutter	O
or	O
to	O
protect	O
privacy	O
.	O
</s>
<s>
Disk	B-Device
space	O
consuming	O
unnecessary	O
files	B-Operating_System
include	O
temporary	B-Application
files	I-Application
,	O
trash	B-Application
,	O
old	O
backups	B-Protocol
and	O
web	B-Protocol
caches	I-Protocol
made	O
by	O
web	O
browsers	O
.	O
</s>
<s>
Privacy	O
risks	O
include	O
HTTP	B-Application
cookies	I-Application
,	O
local	B-Operating_System
shared	I-Operating_System
objects	I-Operating_System
,	O
log	B-Application
files	I-Application
or	O
any	O
other	O
trace	O
that	O
may	O
tell	O
which	O
computer	O
program	O
opened	O
which	O
files	B-Operating_System
.	O
</s>
<s>
Disk	B-Application
cleaners	I-Application
must	O
not	O
be	O
mistaken	O
with	O
antivirus	B-Application
software	I-Application
(	O
which	O
delete	O
malware	O
)	O
,	O
registry	B-Application
cleaners	I-Application
(	O
which	O
clean	O
Microsoft	B-Application
Windows	I-Application
Registry	O
)	O
or	O
data	O
erasure	O
software	O
(	O
which	O
securely	O
delete	O
files	B-Operating_System
)	O
,	O
although	O
multifunction	O
software	O
(	O
such	O
as	O
those	O
included	O
below	O
)	O
may	O
fit	O
into	O
all	O
these	O
categories	O
.	O
</s>
<s>
A	O
disk	B-Device
compression	B-General_Concept
utility	I-General_Concept
increases	O
the	O
amount	O
of	O
information	O
that	O
can	O
be	O
stored	O
on	O
a	O
hard	B-Device
disk	I-Device
drive	I-Device
of	O
given	O
size	O
.	O
</s>
<s>
Unlike	O
a	O
file	B-General_Concept
compression	B-General_Concept
utility	I-General_Concept
which	O
compresses	O
only	O
specified	O
files	B-Operating_System
–	O
and	O
which	O
requires	O
the	O
user	O
designate	O
the	O
files	B-Operating_System
to	O
be	O
compressed	O
–	O
an	O
on-the-fly	O
disk	B-Device
compression	B-General_Concept
utility	I-General_Concept
works	O
automatically	O
without	O
the	O
user	O
needing	O
to	O
be	O
aware	O
of	O
its	O
existence	O
.	O
</s>
<s>
When	O
information	O
needs	O
to	O
be	O
stored	O
to	O
the	O
hard	B-Device
disk	I-Device
,	O
the	O
utility	O
will	O
compress	O
the	O
information	O
.	O
</s>
<s>
A	O
disk	B-Device
compression	B-General_Concept
utility	I-General_Concept
overrides	O
the	O
standard	O
operating	B-General_Concept
system	I-General_Concept
routines	O
.	O
</s>
<s>
Since	O
all	O
software	O
applications	O
access	O
the	O
hard	B-Device
disk	I-Device
using	O
these	O
routines	O
,	O
they	O
continue	O
to	O
work	O
after	O
disk	B-Device
compression	O
has	O
been	O
installed	O
.	O
</s>
<s>
The	O
compression/expansion	O
process	O
adds	O
a	O
small	O
amount	O
of	O
overhead	O
to	O
disk	B-Device
access	O
and	O
may	O
complicate	O
error	O
recovery	O
on	O
the	O
affected	O
volume	O
.	O
</s>
<s>
Also	O
,	O
if	O
the	O
compression	B-General_Concept
utility	I-General_Concept
's	O
device	O
driver	O
was	O
uninstalled	O
or	O
became	O
corrupted	O
,	O
all	O
data	O
on	O
the	O
disk	B-Device
would	O
be	O
lost	O
.	O
</s>
<s>
Disk	B-Device
compression	B-General_Concept
utilities	I-General_Concept
were	O
popular	O
especially	O
in	O
the	O
early	O
1990s	O
,	O
when	O
microcomputer	O
hard	B-Device
disks	I-Device
were	O
still	O
relatively	O
small	O
(	O
20	O
to	O
80	O
megabytes	O
)	O
.	O
</s>
<s>
Hard	B-Device
drives	I-Device
were	O
also	O
rather	O
expensive	O
at	O
the	O
time	O
,	O
costing	O
roughly	O
10	O
USD	O
per	O
megabyte	O
.	O
</s>
<s>
For	O
the	O
users	O
who	O
bought	O
disk	B-Device
compression	O
applications	O
,	O
the	O
software	O
proved	O
to	O
be	O
in	O
the	O
short	O
term	O
a	O
more	O
economic	O
means	O
of	O
acquiring	O
more	O
disk	B-Device
space	O
as	O
opposed	O
to	O
replacing	O
their	O
current	O
drive	O
with	O
a	O
larger	O
one	O
.	O
</s>
<s>
A	O
good	O
disk	B-Device
compression	B-General_Concept
utility	I-General_Concept
could	O
,	O
on	O
average	O
,	O
double	O
the	O
available	O
space	O
with	O
negligible	O
speed	O
loss	O
.	O
</s>
<s>
Disk	B-Device
compression	O
fell	O
into	O
disuse	O
by	O
the	O
late	O
1990s	O
,	O
as	O
advances	O
in	O
hard	B-Device
drive	I-Device
technology	O
and	O
manufacturing	O
led	O
to	O
increased	O
capacities	O
and	O
lower	O
prices	O
.	O
</s>
<s>
Some	O
examples	O
of	O
disk	B-Device
compression	B-General_Concept
utilities	I-General_Concept
:	O
</s>
<s>
A	O
disk	B-Application
checker	I-Application
is	O
a	O
utility	B-Application
program	I-Application
which	O
can	O
scan	O
a	O
hard	B-Device
disk	I-Device
to	O
find	O
files	B-Operating_System
or	O
areas	O
that	O
are	O
corrupted	O
in	O
some	O
way	O
,	O
or	O
were	O
not	O
correctly	O
saved	O
,	O
and	O
eliminate	O
them	O
for	O
a	O
more	O
efficiently	O
operating	O
hard	B-Device
drive	I-Device
.	O
</s>
<s>
This	O
is	O
not	O
to	O
be	O
confused	O
with	O
a	O
disk	B-Application
cleaner	I-Application
,	O
which	O
can	O
find	O
files	B-Operating_System
that	O
are	O
unnecessary	O
for	O
computer	O
operation	O
,	O
or	O
take	O
up	O
considerable	O
amounts	O
of	O
space	O
.	O
</s>
<s>
Some	O
disk	B-Application
checkers	I-Application
can	O
perform	O
a	O
whole	O
surface	O
scan	O
to	O
attempt	O
to	O
find	O
any	O
possible	O
bad	B-Device
sectors	I-Device
,	O
whereas	O
others	O
scan	O
only	O
the	O
logical	O
structure	O
of	O
files	B-Operating_System
on	O
the	O
hard	B-Device
disk	I-Device
.	O
</s>
<s>
Operating	B-General_Concept
systems	I-General_Concept
often	O
include	O
one	O
such	O
tool	O
.	O
</s>
<s>
Disk	B-Application
formatting	I-Application
and	O
disk	B-Application
partitioning	I-Application
tools	O
are	O
responsible	O
for	O
generating	O
low	O
level	O
disk	B-Device
layouts	O
and	O
file	B-Application
systems	I-Application
.	O
</s>
<s>
Operating	B-General_Concept
systems	I-General_Concept
typically	O
supply	O
one	O
or	O
more	O
programs	O
performing	O
these	O
functions	O
as	O
part	O
of	O
their	O
standard	O
install	O
:	O
</s>
<s>
In	O
Linux	B-Application
:	O
</s>
<s>
A	O
disk	B-Device
space	O
analyzer	O
(	O
or	O
disk	B-Device
usage	O
analysis	O
software	O
)	O
is	O
a	O
software	B-Application
utility	I-Application
for	O
the	O
visualization	O
of	O
disk	B-Device
space	O
usage	O
by	O
getting	O
the	O
size	O
for	O
each	O
folder	O
(	O
including	O
sub-folders	O
)	O
and	O
files	B-Operating_System
in	O
a	O
folder	O
or	O
drive	O
.	O
</s>
<s>
Most	O
of	O
these	O
applications	O
analyze	O
this	O
information	O
to	O
generate	O
a	O
graphical	O
chart	O
showing	O
disk	B-Device
usage	O
distribution	O
according	O
to	O
folders	O
or	O
other	O
user	O
defined	O
criteria	O
.	O
</s>
<s>
Some	O
disk	B-Device
space	O
analyzers	O
like	O
DiskReport	O
allow	O
analysis	O
of	O
history	O
of	O
size	O
and	O
file	O
count	O
for	O
each	O
folder	O
,	O
to	O
help	O
find	O
growing	O
folders	O
.	O
</s>
