<s>
FSCAN	B-General_Concept
is	O
a	O
disk	B-General_Concept
scheduling	I-General_Concept
algorithm	O
to	O
determine	O
the	O
motion	O
of	O
the	O
disk	O
's	O
arm	O
and	O
head	O
in	O
servicing	O
read	O
and	O
write	O
requests	O
.	O
</s>
<s>
It	O
uses	O
two	O
sub-queues	O
.	O
</s>
<s>
During	O
the	O
scan	B-Algorithm
,	O
all	O
of	O
the	O
requests	O
are	O
in	O
the	O
first	O
queue	B-Application
and	O
all	O
new	O
requests	O
are	O
put	O
into	O
the	O
second	O
queue	B-Application
.	O
</s>
<s>
When	O
the	O
scan	B-Algorithm
ends	O
,	O
the	O
arm	O
is	O
taken	O
to	O
the	O
first	O
queue	B-Application
entries	O
and	O
is	O
started	O
all	O
over	O
again	O
.	O
</s>
<s>
FSCAN	B-General_Concept
along	O
with	O
N-Step-SCAN	O
prevents	O
"	O
arm	O
stickiness	O
"	O
unlike	O
SSTF	B-General_Concept
,	O
SCAN	B-Algorithm
,	O
and	O
C-SCAN	B-Algorithm
.	O
</s>
<s>
Because	O
FSCAN	B-General_Concept
separates	O
requests	O
into	O
two	O
queues	B-Application
,	O
with	O
new	O
requests	O
going	O
into	O
a	O
waiting	O
queue	B-Application
,	O
the	O
arm	O
continues	O
its	O
sweep	O
to	O
the	O
outer	O
track	O
and	O
is	O
therefore	O
not	O
"	O
sticky.	O
"	O
</s>
<s>
There	O
is	O
an	O
obvious	O
trade-off	O
in	O
that	O
the	O
requests	O
in	O
the	O
waiting	O
queue	B-Application
must	O
wait	O
longer	O
to	O
be	O
fulfilled	O
,	O
but	O
in	O
exchange	O
FSCAN	B-General_Concept
is	O
more	O
fair	O
to	O
all	O
requests	O
.	O
</s>
<s>
Instead	O
of	O
using	O
just	O
2	O
queues	B-Application
,	O
one	O
can	O
use	O
N	O
queues	B-Application
(	O
with	O
N	O
greater	O
than	O
2	O
)	O
.	O
</s>
<s>
The	O
benefit	O
of	O
using	O
N	O
queues	B-Application
is	O
there	O
would	O
be	O
limited	O
number	O
of	O
entries	O
in	O
a	O
given	O
queue	B-Application
and	O
hence	O
the	O
reference	O
string	O
queue	B-Application
would	O
take	O
lesser	O
time	O
to	O
get	O
completed	O
.	O
</s>
<s>
Hence	O
,	O
the	O
queues	B-Application
will	O
get	O
swiped	O
faster	O
which	O
in	O
turn	O
improves	O
the	O
responding	O
time	O
of	O
algorithm	O
(	O
refer	O
to	O
See	O
Also	O
section	O
)	O
.	O
</s>
