<s>
A	O
parity	B-General_Concept
drive	I-General_Concept
is	O
a	O
hard	B-Device
drive	I-Device
used	O
in	O
a	O
RAID	B-Architecture
array	I-Architecture
to	O
provide	O
fault	B-General_Concept
tolerance	I-General_Concept
.	O
</s>
<s>
For	O
example	O
,	O
RAID	B-Architecture
3	O
uses	O
a	O
parity	B-General_Concept
drive	I-General_Concept
to	O
create	O
a	O
system	O
that	O
is	O
both	O
fault	B-General_Concept
tolerant	I-General_Concept
and	O
,	O
because	O
of	O
data	B-General_Concept
striping	I-General_Concept
,	O
fast	O
.	O
</s>
<s>
One	O
way	O
to	O
implement	O
a	O
parity	B-General_Concept
drive	I-General_Concept
in	O
a	O
RAID	B-Architecture
array	I-Architecture
is	O
to	O
use	O
the	O
exclusive	O
or	O
,	O
or	O
XOR	O
,	O
function	O
.	O
</s>
<s>
The	O
XOR	O
of	O
all	O
of	O
the	O
data	O
drives	O
in	O
the	O
RAID	B-Architecture
array	I-Architecture
is	O
written	O
to	O
the	O
parity	B-General_Concept
drive	I-General_Concept
.	O
</s>
