<s>
Input/output	B-General_Concept
(	O
I/O	B-General_Concept
)	O
scheduling	B-Application
is	O
the	O
method	O
that	O
computer	B-General_Concept
operating	I-General_Concept
systems	I-General_Concept
use	O
to	O
decide	O
in	O
which	O
order	O
I/O	B-General_Concept
operations	I-General_Concept
will	O
be	O
submitted	O
to	O
storage	B-Application
volumes	I-Application
.	O
</s>
<s>
I/O	B-General_Concept
scheduling	I-General_Concept
is	O
sometimes	O
called	O
disk	B-General_Concept
scheduling	I-General_Concept
.	O
</s>
<s>
I/O	B-General_Concept
scheduling	I-General_Concept
usually	O
has	O
to	O
work	O
with	O
hard	B-Device
disk	I-Device
drives	I-Device
that	O
have	O
long	O
access	B-General_Concept
times	I-General_Concept
for	O
requests	O
placed	O
far	O
away	O
from	O
the	O
current	O
position	O
of	O
the	O
disk	O
head	O
(	O
this	O
operation	O
is	O
called	O
a	O
seek	O
)	O
.	O
</s>
<s>
To	O
minimize	O
the	O
effect	O
this	O
has	O
on	O
system	O
performance	O
,	O
most	O
I/O	B-General_Concept
schedulers	I-General_Concept
implement	O
a	O
variant	O
of	O
the	O
elevator	B-Algorithm
algorithm	I-Algorithm
that	O
reorders	O
the	O
incoming	O
randomly	O
ordered	O
requests	O
so	O
the	O
associated	O
data	O
would	O
be	O
accessed	O
with	O
minimal	O
arm/head	O
movement	O
.	O
</s>
<s>
Common	O
scheduling	B-Application
disciplines	O
include	O
the	O
following	O
:	O
</s>
