<s>
Parallel	B-Operating_System
I/O	I-Operating_System
,	O
in	O
the	O
context	O
of	O
a	O
computer	O
,	O
means	O
the	O
performance	O
of	O
multiple	O
input/output	B-General_Concept
operations	O
at	O
the	O
same	O
time	O
,	O
for	O
instance	O
simultaneously	O
outputs	O
to	O
storage	O
devices	O
and	O
display	O
devices	O
.	O
</s>
<s>
It	O
is	O
a	O
fundamental	O
feature	O
of	O
operating	B-General_Concept
systems	I-General_Concept
.	O
</s>
<s>
One	O
particular	O
instance	O
is	O
parallel	O
writing	O
of	O
data	O
to	O
disk	O
;	O
when	O
file	O
data	O
is	O
spread	O
across	O
multiple	O
disks	O
,	O
for	O
example	O
in	O
a	O
RAID	B-Architecture
array	I-Architecture
,	O
one	O
can	O
store	O
multiple	O
parts	O
of	O
the	O
data	O
at	O
the	O
same	O
time	O
,	O
thereby	O
achieving	O
higher	O
write	O
speeds	O
than	O
with	O
a	O
single	O
device	O
.	O
</s>
<s>
Other	O
ways	O
of	O
parallel	O
access	O
to	O
data	O
include	O
:	O
Parallel	B-Application
Virtual	I-Application
File	I-Application
System	I-Application
,	O
Lustre	B-Application
,	O
GFS	B-Application
etc	O
.	O
</s>
<s>
It	O
breaks	O
up	O
support	O
into	O
multiple	O
layers	O
including	O
High	O
level	O
I/O	B-General_Concept
library	O
,	O
Middleware	O
layer	O
and	O
Parallel	O
file	O
system	O
.	O
</s>
<s>
The	O
caches	O
are	O
larger	O
in	O
Parallel	B-Operating_System
I/O	I-Operating_System
and	O
shared	O
through	O
distributed	O
memory	O
systems	O
.	O
</s>
<s>
Companies	O
have	O
been	O
running	O
Parallel	B-Operating_System
I/O	I-Operating_System
on	O
their	O
servers	O
to	O
achieve	O
results	O
with	O
regard	O
to	O
price	O
and	O
performance	O
.	O
</s>
<s>
Parallel	O
processing	O
is	O
especially	O
critical	O
for	O
scientific	O
calculations	O
where	O
applications	O
are	O
not	O
only	O
CPU	O
but	O
also	O
are	O
I/O	B-General_Concept
bound	O
.	O
</s>
