<s>
Disk	B-Application
partitioning	I-Application
or	O
disk	O
slicing	O
is	O
the	O
creation	O
of	O
one	O
or	O
more	O
regions	O
on	O
secondary	O
storage	O
,	O
so	O
that	O
each	O
region	O
can	O
be	O
managed	O
separately	O
.	O
</s>
<s>
These	O
regions	O
are	O
called	O
partitions	B-Application
.	O
</s>
<s>
It	O
is	O
typically	O
the	O
first	O
step	O
of	O
preparing	O
a	O
newly	O
installed	O
disk	O
,	O
before	O
any	O
file	B-Application
system	I-Application
is	O
created	O
.	O
</s>
<s>
The	O
disk	O
stores	O
the	O
information	O
about	O
the	O
partitions	B-Application
 '	O
locations	O
and	O
sizes	O
in	O
an	O
area	O
known	O
as	O
the	O
partition	B-Application
table	O
that	O
the	O
operating	O
system	O
reads	O
before	O
any	O
other	O
part	O
of	O
the	O
disk	O
.	O
</s>
<s>
Each	O
partition	B-Application
then	O
appears	O
to	O
the	O
operating	O
system	O
as	O
a	O
distinct	O
"	O
logical	O
"	O
disk	O
that	O
uses	O
part	O
of	O
the	O
actual	O
disk	O
.	O
</s>
<s>
System	B-Application
administrators	I-Application
use	O
a	O
program	O
called	O
a	O
partition	B-Application
editor	O
to	O
create	O
,	O
resize	O
,	O
delete	O
,	O
and	O
manipulate	O
the	O
partitions	B-Application
.	O
</s>
<s>
Partitioning	B-Application
allows	O
the	O
use	O
of	O
different	O
filesystems	B-Application
to	O
be	O
installed	O
for	O
different	O
kinds	O
of	O
files	O
.	O
</s>
<s>
Separating	O
user	O
data	O
from	O
system	O
data	O
can	O
prevent	O
the	O
system	B-Application
partition	I-Application
from	O
becoming	O
full	O
and	O
rendering	O
the	O
system	O
unusable	O
.	O
</s>
<s>
Partitioning	B-Application
can	O
also	O
make	O
backing	O
up	O
easier	O
.	O
</s>
<s>
A	O
disadvantage	O
is	O
that	O
it	O
can	O
be	O
difficult	O
to	O
properly	O
size	O
partitions	B-Application
,	O
resulting	O
in	O
having	O
one	O
partition	B-Application
with	O
too	O
much	O
free	O
space	O
and	O
another	O
nearly	O
totally	O
allocated	O
.	O
</s>
<s>
IBM	O
in	O
its	O
1983	O
release	O
of	O
PC	O
DOS	B-Device
version	O
2.0	O
was	O
an	O
early	O
if	O
not	O
first	O
use	O
of	O
the	O
term	O
partition	B-Application
to	O
describe	O
dividing	O
a	O
block	O
storage	O
device	O
such	O
as	O
an	O
HDD	B-Device
into	O
physical	O
segments	O
.	O
</s>
<s>
Other	O
terms	O
used	O
in	O
the	O
art	O
have	O
included	O
logical	O
disk	O
,	O
minidisk	O
,	O
portions	O
,	O
pseudo-disk	O
,	O
section	O
,	O
slice	B-Application
and	O
virtual	O
drive	O
.	O
</s>
<s>
One	O
of	O
the	O
earliest	O
such	O
segmentation	O
of	O
a	O
disk	O
drive	O
was	O
IBM	O
's	O
1966	O
usage	O
in	O
its	O
CP-67	B-Application
operating	O
system	O
of	O
minidisk	O
as	O
a	O
separate	O
segment	O
of	O
a	O
hard	B-Device
disk	I-Device
drive	I-Device
.	O
</s>
<s>
With	O
DOS	B-Device
,	O
Microsoft	B-Application
Windows	I-Application
,	O
and	O
OS/2	B-Application
,	O
a	O
common	O
practice	O
is	O
to	O
use	O
one	O
primary	O
partition	B-Application
for	O
the	O
active	O
file	B-Application
system	I-Application
that	O
will	O
contain	O
the	O
operating	O
system	O
,	O
the	O
page/swap	O
file	O
,	O
all	O
utilities	O
,	O
applications	O
,	O
and	O
user	O
data	O
.	O
</s>
<s>
On	O
most	O
Windows	B-Application
consumer	O
computers	O
,	O
the	O
drive	O
letter	O
C	O
:	O
is	O
routinely	O
assigned	O
to	O
this	O
primary	O
partition	B-Application
.	O
</s>
<s>
Other	O
partitions	B-Application
may	O
exist	O
on	O
the	O
HDD	B-Device
that	O
may	O
or	O
may	O
not	O
be	O
visible	O
as	O
drives	O
,	O
such	O
as	O
recovery	O
partitions	B-Application
or	O
partitions	B-Application
with	O
diagnostic	O
tools	O
or	O
data	O
.	O
</s>
<s>
(	O
Windows	B-Application
drive	O
letters	O
do	O
not	O
correspond	O
to	O
partitions	B-Application
in	O
a	O
one-to-one	O
fashion	O
,	O
so	O
there	O
may	O
be	O
more	O
or	O
fewer	O
drive	O
letters	O
than	O
partitions	B-Application
.	O
)	O
</s>
<s>
Microsoft	B-Application
Windows	I-Application
2000	I-Application
,	O
XP	B-Application
,	O
Vista	B-Application
,	O
and	O
Windows	B-Device
7	I-Device
include	O
a	O
'	O
Disk	O
Management	O
 '	O
program	O
which	O
allows	O
for	O
the	O
creation	O
,	O
deletion	O
and	O
resizing	O
of	O
FAT	B-Application
and	O
NTFS	B-Application
partitions	B-Application
.	O
</s>
<s>
The	O
Windows	B-Application
Disk	O
Manager	O
in	O
Windows	B-Application
Vista	I-Application
and	O
Windows	B-Device
7	I-Device
utilizes	O
a	O
1	O
MB	O
partition	B-Application
alignment	O
scheme	O
which	O
is	O
fundamentally	O
incompatible	O
with	O
Windows	B-Application
2000	I-Application
,	O
XP	B-Application
,	O
OS/2	B-Application
,	O
DOS	B-Device
as	O
well	O
as	O
many	O
other	O
operating	O
systems	O
.	O
</s>
<s>
On	O
Unix-based	O
and	O
Unix-like	B-Operating_System
operating	I-Operating_System
systems	I-Operating_System
such	O
as	O
Linux	B-Application
,	O
macOS	B-Application
,	O
BSD	B-Operating_System
,	O
and	O
Solaris	B-Application
,	O
it	O
is	O
possible	O
to	O
use	O
multiple	O
partitions	B-Application
on	O
a	O
disk	O
device	O
.	O
</s>
<s>
Each	O
partition	B-Application
can	O
be	O
formatted	O
with	O
a	O
file	B-Application
system	I-Application
or	O
as	O
a	O
swap	O
partition	B-Application
.	O
</s>
<s>
Multiple	O
partitions	B-Application
allow	O
directories	O
such	O
as	O
/boot	B-Application
,	O
/tmp	O
,	O
/usr	O
,	O
/var	O
,	O
or	O
/home	B-Application
to	O
be	O
allocated	O
their	O
own	O
filesystems	B-Application
.	O
</s>
<s>
If	O
one	O
file	B-Application
system	I-Application
gets	O
corrupted	O
,	O
the	O
data	O
outside	O
that	O
filesystem/partition	O
may	O
stay	O
intact	O
,	O
minimizing	O
data	O
loss	O
.	O
</s>
<s>
Specific	O
file	B-Application
systems	I-Application
can	O
be	O
mounted	O
with	O
different	O
parameters	O
,	O
e.g.	O
,	O
read-only	O
,	O
or	O
with	O
the	O
execution	O
of	O
setuid	O
files	O
disabled	O
.	O
</s>
<s>
A	O
runaway	O
program	O
that	O
uses	O
up	O
all	O
available	O
space	O
on	O
a	O
non-system	O
filesystem	B-Application
does	O
not	O
fill	O
up	O
critical	O
filesystems	B-Application
.	O
</s>
<s>
A	O
common	O
minimal	O
configuration	O
for	O
Linux	B-Application
systems	O
is	O
to	O
use	O
three	O
partitions	B-Application
:	O
one	O
holding	O
the	O
system	O
files	O
mounted	O
on	O
"	O
/	O
"	O
(	O
the	O
root	B-Application
directory	I-Application
)	O
,	O
one	O
holding	O
user	O
configuration	O
files	O
and	O
data	O
mounted	O
on	O
/home	B-Application
(	O
home	B-Application
directory	I-Application
)	O
,	O
and	O
a	O
swap	O
partition	B-Application
.	O
</s>
<s>
By	O
default	O
,	O
macOS	B-Application
systems	O
also	O
use	O
a	O
single	O
partition	B-Application
for	O
the	O
entire	O
filesystem	B-Application
and	O
use	O
a	O
swap	O
file	O
inside	O
the	O
file	B-Application
system	I-Application
(	O
like	O
Windows	B-Application
)	O
rather	O
than	O
a	O
swap	O
partition	B-Application
.	O
</s>
<s>
In	O
Solaris	B-Application
,	O
partitions	B-Application
are	O
sometimes	O
known	O
as	O
slices	B-Application
.	O
</s>
<s>
The	O
term	O
"	O
slice	B-Application
"	O
is	O
used	O
in	O
the	O
FreeBSD	B-Operating_System
operating	O
system	O
to	O
refer	O
to	O
Master	B-Device
Boot	I-Device
Record	I-Device
partitions	B-Application
,	O
to	O
avoid	O
confusion	O
with	O
FreeBSD	B-Operating_System
's	O
own	O
disklabel-based	O
partitioning	B-Application
scheme	O
.	O
</s>
<s>
However	O
,	O
GUID	B-Application
Partition	I-Application
Table	I-Application
partitions	B-Application
are	O
referred	O
to	O
as	O
"	O
partition	B-Application
"	O
worldwide	O
.	O
</s>
<s>
Multi-boot	O
systems	O
are	O
computers	O
where	O
the	O
user	O
can	O
boot	B-Operating_System
into	O
more	O
than	O
one	O
distinct	O
operating	O
system	O
(	O
OS	O
)	O
stored	O
in	O
separate	O
storage	O
devices	O
or	O
in	O
separate	O
partitions	B-Application
of	O
the	O
same	O
storage	O
device	O
.	O
</s>
<s>
In	O
such	O
systems	O
a	O
menu	O
at	O
startup	B-Operating_System
gives	O
a	O
choice	O
of	O
which	O
OS	O
to	O
boot/start	O
(	O
and	O
only	O
one	O
OS	O
at	O
a	O
time	O
is	O
loaded	O
)	O
.	O
</s>
<s>
This	O
is	O
distinct	O
from	O
virtual	B-Architecture
operating	I-Architecture
systems	I-Architecture
,	O
in	O
which	O
one	O
operating	O
system	O
is	O
run	O
as	O
a	O
self-contained	O
virtual	O
"	O
program	O
"	O
within	O
another	O
already-running	O
operating	O
system	O
.	O
</s>
<s>
(	O
An	O
example	O
is	O
a	O
Windows	B-Application
OS	I-Application
"	O
virtual	B-Architecture
machine	I-Architecture
"	O
running	O
from	O
within	O
a	O
Linux	B-Application
OS	I-Application
.	O
)	O
</s>
<s>
The	O
GUID	B-Application
Partition	I-Application
Table	I-Application
(	O
Globally	O
Unique	O
IDentifier	O
)	O
is	O
a	O
part	O
of	O
the	O
Unified	B-Architecture
Extensible	I-Architecture
Firmware	I-Architecture
Interface	I-Architecture
(	O
UEFI	B-Architecture
)	O
standard	O
for	O
the	O
layout	O
of	O
the	O
partition	B-Application
table	O
on	O
a	O
physical	O
hard	B-Device
disk	I-Device
.	O
</s>
<s>
However	O
,	O
Windows	B-Application
does	O
n't	O
support	O
this	O
on	O
BIOS	B-Operating_System
based	O
computers	O
.	O
</s>
<s>
When	O
a	O
partition	B-Application
is	O
deleted	O
,	O
its	O
entry	O
is	O
removed	O
from	O
a	O
table	O
and	O
the	O
data	O
is	O
no	O
longer	O
accessible	O
.	O
</s>
<s>
Specialized	O
recovery	O
utilities	O
may	O
be	O
able	O
to	O
locate	O
lost	O
file	B-Application
systems	I-Application
and	O
recreate	O
a	O
partition	B-Application
table	O
which	O
includes	O
entries	O
for	O
these	O
recovered	O
file	B-Application
systems	I-Application
.	O
</s>
<s>
Some	O
disk	O
utilities	O
may	O
overwrite	O
a	O
number	O
of	O
beginning	O
sectors	O
of	O
a	O
partition	B-Application
they	O
delete	O
.	O
</s>
<s>
For	O
example	O
,	O
if	O
Windows	B-Application
Disk	O
Management	O
(	O
Windows	B-Application
2000/XP	O
,	O
etc	O
.	O
)	O
</s>
<s>
is	O
used	O
to	O
delete	O
a	O
partition	B-Application
,	O
it	O
will	O
overwrite	O
the	O
first	O
sector	O
(	O
relative	O
sector	O
0	O
)	O
of	O
the	O
partition	B-Application
before	O
removing	O
it	O
.	O
</s>
<s>
It	O
still	O
may	O
be	O
possible	O
to	O
restore	O
a	O
FAT	B-Application
or	O
NTFS	B-Application
partition	B-Application
if	O
a	O
backup	O
boot	B-Operating_System
sector	O
is	O
available	O
.	O
</s>
<s>
In	O
DOS	B-Device
and	O
early	O
Microsoft	B-Application
Windows	I-Application
,	O
programs	O
such	O
as	O
Stacker	O
(	O
DR-DOS	O
except	O
6.0	O
)	O
,	O
SuperStor	O
(	O
DRDOS	O
6.0	O
)	O
,	O
DoubleSpace	B-General_Concept
(	O
MS-DOS	O
6.0	O
–	O
6.2	O
)	O
,	O
or	O
DriveSpace	B-General_Concept
(	O
MS-DOS	O
6.22	O
,	O
Windows	B-Application
9x	O
)	O
were	O
used	O
.	O
</s>
<s>
This	O
compression	O
was	O
done	O
by	O
creating	O
a	O
very	O
large	O
file	O
on	O
the	O
partition	B-Application
,	O
then	O
storing	O
the	O
disk	O
's	O
data	O
in	O
this	O
file	O
.	O
</s>
<s>
At	O
startup	B-Operating_System
,	O
device	O
drivers	O
opened	O
this	O
file	O
and	O
assigned	O
it	O
a	O
separate	O
letter	O
.	O
</s>
<s>
Frequently	O
,	O
to	O
avoid	O
confusion	O
,	O
the	O
original	O
partition	B-Application
and	O
the	O
compressed	O
drive	O
had	O
their	O
letters	O
swapped	O
,	O
so	O
that	O
the	O
compressed	O
disk	O
is	O
C	O
:	O
,	O
and	O
the	O
uncompressed	O
area	O
(	O
often	O
containing	O
system	O
files	O
)	O
is	O
given	O
a	O
higher	O
name	O
.	O
</s>
<s>
Versions	O
of	O
Windows	B-Application
using	O
the	O
NT	O
kernel	O
,	O
including	O
the	O
most	O
recent	O
version	O
,	O
Windows	B-Operating_System
10	I-Operating_System
,	O
contain	O
intrinsic	O
disk	O
compression	O
capability	O
.	O
</s>
<s>
A	O
partition	B-Application
table	O
is	O
a	O
table	O
maintained	O
on	O
a	O
disk	O
by	O
the	O
operating	O
system	O
that	O
outlines	O
and	O
describes	O
the	O
partitions	B-Application
on	O
that	O
disk	O
.	O
</s>
<s>
The	O
terms	O
partition	B-Application
table	O
and	O
partition	B-Application
map	O
are	O
similar	O
terms	O
and	O
can	O
be	O
used	O
interchangeably	O
.	O
</s>
<s>
The	O
term	O
is	O
most	O
commonly	O
associated	O
with	O
the	O
MBR	O
partition	B-Application
table	O
of	O
a	O
Master	B-Device
Boot	I-Device
Record	I-Device
(	O
MBR	O
)	O
in	O
PCs	B-Device
,	O
but	O
it	O
may	O
be	O
used	O
generically	O
to	O
refer	O
to	O
other	O
formats	O
that	O
divide	O
a	O
disk	O
drive	O
into	O
partitions	B-Application
,	O
such	O
as	O
:	O
GUID	B-Application
Partition	I-Application
Table	I-Application
(	O
GPT	O
)	O
,	O
Apple	B-Application
partition	I-Application
map	I-Application
(	O
APM	O
)	O
,	O
or	O
BSD	B-Application
disklabel	I-Application
.	O
</s>
<s>
This	O
section	O
describes	O
the	O
master	B-Device
boot	I-Device
record	I-Device
(	O
MBR	O
)	O
partitioning	B-Application
scheme	O
,	O
as	O
used	O
historically	O
in	O
DOS	B-Device
,	O
Microsoft	B-Application
Windows	I-Application
and	O
Linux	B-Application
(	O
among	O
others	O
)	O
on	O
PC-compatible	O
computer	O
systems	O
.	O
</s>
<s>
As	O
of	O
the	O
mid-2010s	O
,	O
most	O
new	O
computers	O
use	O
the	O
GUID	B-Application
Partition	I-Application
Table	I-Application
(	O
GPT	O
)	O
partitioning	B-Application
scheme	O
instead	O
.	O
</s>
<s>
For	O
examples	O
of	O
other	O
partitioning	B-Application
schemes	O
,	O
see	O
the	O
general	O
article	O
on	O
partition	B-Application
tables	O
.	O
</s>
<s>
The	O
total	O
data	O
storage	O
space	O
of	O
a	O
PC	O
HDD	B-Device
on	O
which	O
MBR	O
partitioning	B-Application
is	O
implemented	O
can	O
contain	O
at	O
most	O
four	O
primary	O
partitions	B-Application
,	O
or	O
alternatively	O
three	O
primary	O
partitions	B-Application
and	O
an	O
extended	B-Application
partition	I-Application
.	O
</s>
<s>
The	O
Partition	B-Application
Table	O
,	O
located	O
in	O
the	O
master	B-Device
boot	I-Device
record	I-Device
,	O
contains	O
16-byte	O
entries	O
,	O
each	O
of	O
which	O
describes	O
a	O
partition	B-Application
.	O
</s>
<s>
The	O
partition	B-Application
type	O
is	O
identified	O
by	O
a	O
1-byte	O
code	O
found	O
in	O
its	O
partition	B-Application
table	O
entry	O
.	O
</s>
<s>
Some	O
of	O
these	O
codes	O
(	O
such	O
as	O
and	O
)	O
may	O
be	O
used	O
to	O
indicate	O
the	O
presence	O
of	O
an	O
extended	B-Application
partition	I-Application
.	O
</s>
<s>
Most	O
are	O
used	O
by	O
an	O
operating	O
system	O
's	O
bootloader	B-Application
(	O
that	O
examines	O
partition	B-Application
tables	O
)	O
to	O
decide	O
if	O
a	O
partition	B-Application
contains	O
a	O
file	B-Application
system	I-Application
that	O
can	O
be	O
mounted	O
/	O
accessed	O
for	O
reading	O
or	O
writing	O
data	O
.	O
</s>
<s>
A	O
primary	O
partition	B-Application
contains	O
one	O
file	B-Application
system	I-Application
.	O
</s>
<s>
In	O
DOS	B-Device
and	O
all	O
early	O
versions	O
of	O
Microsoft	B-Application
Windows	I-Application
systems	O
,	O
Microsoft	O
required	O
what	O
it	O
called	O
the	O
system	B-Application
partition	I-Application
to	O
be	O
the	O
first	O
partition	B-Application
.	O
</s>
<s>
All	O
Windows	B-Application
operating	I-Application
systems	I-Application
from	O
Windows	B-Application
95	O
onwards	O
can	O
be	O
located	O
on	O
(	O
almost	O
)	O
any	O
partition	B-Application
,	O
but	O
the	O
boot	B-Operating_System
files	O
(	O
io.sys	O
,	O
bootmgr	O
,	O
ntldr	O
,	O
etc	O
.	O
)	O
</s>
<s>
must	O
reside	O
on	O
a	O
primary	O
partition	B-Application
.	O
</s>
<s>
However	O
,	O
other	O
factors	O
,	O
such	O
as	O
a	O
PC	O
's	O
BIOS	B-Operating_System
(	O
see	O
Boot	B-Operating_System
sequence	I-Operating_System
on	O
standard	O
PC	O
)	O
may	O
also	O
impose	O
specific	O
requirements	O
as	O
to	O
which	O
partition	B-Application
must	O
contain	O
the	O
primary	O
OS	O
.	O
</s>
<s>
The	O
partition	B-Application
type	O
code	O
for	O
a	O
primary	O
partition	B-Application
can	O
either	O
correspond	O
to	O
a	O
file	B-Application
system	I-Application
contained	O
within	O
(	O
e.g.	O
,	O
means	O
either	O
an	O
NTFS	B-Application
or	O
an	O
OS/2	B-Application
HPFS	I-Application
file	B-Application
system	I-Application
)	O
or	O
indicate	O
that	O
the	O
partition	B-Application
has	O
a	O
special	O
use	O
(	O
e.g.	O
,	O
code	O
usually	O
indicates	O
a	O
Linux	B-Application
swap	O
partition	B-Application
)	O
.	O
</s>
<s>
The	O
FAT16	B-Application
and	O
FAT32	B-Application
file	B-Application
systems	I-Application
have	O
made	O
use	O
of	O
a	O
number	O
of	O
partition	B-Application
type	O
codes	O
due	O
to	O
the	O
limits	O
of	O
various	O
DOS	B-Device
and	O
Windows	B-Application
OS	I-Application
versions	O
.	O
</s>
<s>
Though	O
a	O
Linux	B-Application
operating	I-Application
system	I-Application
may	O
recognize	O
a	O
number	O
of	O
different	O
file	B-Application
systems	I-Application
(	O
ext4	B-Application
,	O
ext3	B-Application
,	O
ext2	B-Application
,	O
ReiserFS	B-Application
,	O
etc	O
.	O
</s>
<s>
)	O
,	O
they	O
have	O
all	O
consistently	O
used	O
the	O
same	O
partition	B-Application
type	O
code	O
:	O
(	O
Linux	B-Application
native	O
file	B-Application
system	I-Application
)	O
.	O
</s>
<s>
An	O
HDD	B-Device
may	O
contain	O
only	O
one	O
extended	B-Application
partition	I-Application
,	O
but	O
that	O
extended	B-Application
partition	I-Application
can	O
be	O
subdivided	O
into	O
multiple	O
logical	O
partitions	B-Application
.	O
</s>
<s>
DOS/Windows	O
systems	O
may	O
then	O
assign	O
a	O
unique	O
drive	O
letter	O
to	O
each	O
logical	O
partition	B-Application
.	O
</s>
<s>
GUID	B-Application
partition	I-Application
table	I-Application
(	O
GPT	O
)	O
only	O
has	O
the	O
primary	O
partition	B-Application
,	O
does	O
n't	O
have	O
the	O
extended	B-Application
partition	I-Application
and	O
the	O
logical	O
partition	B-Application
.	O
</s>
<s>
BIOS	B-Operating_System
boot	B-Application
partition	I-Application
(	O
BIOS	B-Operating_System
BP	O
)	O
is	O
a	O
share	O
of	O
the	O
storage	O
device	O
used	O
to	O
keep	O
software	O
that	O
boots	O
the	O
operating	O
system	O
,	O
a	O
bootloader	B-Application
.	O
</s>
<s>
It	O
may	O
be	O
an	O
operating	O
system	O
kernel	O
image	O
or	O
bootloader	B-Application
or	O
a	O
completely	O
separate	O
piece	O
of	O
software	O
.	O
</s>
<s>
EFI	B-Device
system	I-Device
partition	I-Device
is	O
the	O
same	O
as	O
BIOS	B-Operating_System
BP	O
,	O
but	O
is	O
loaded	O
by	O
EFI	O
firmware	O
instead	O
of	O
BIOS	B-Operating_System
.	O
</s>
