<s>
In	O
block	B-General_Concept
storage	I-General_Concept
devices	O
such	O
as	O
hard	B-Device
disk	I-Device
drives	I-Device
,	O
interleaving	B-Application
is	O
a	O
technique	O
used	O
to	O
improve	O
slow	O
system	O
performance	O
by	O
putting	O
data	O
accessed	O
sequentially	O
into	O
non-sequential	O
blocks	O
,	O
typically	O
sectors	B-Application
.	O
</s>
<s>
The	O
number	O
of	O
physical	O
sectors	B-Application
between	O
consecutive	O
logical	O
sectors	B-Application
is	O
called	O
the	O
interleave	O
skip	B-Application
factor	I-Application
or	O
skip	B-Application
factor	I-Application
.	O
</s>
<s>
Ordering	O
block	B-General_Concept
storage	I-General_Concept
on	O
storage	O
devices	O
such	O
as	O
drums	B-General_Concept
,	O
floppy	B-Device
disk	I-Device
drives	I-Device
and	O
hard	B-Device
disk	I-Device
drives	I-Device
.	O
</s>
<s>
The	O
purpose	O
of	O
interleaving	B-Application
was	O
to	O
adjust	O
the	O
time	O
difference	O
between	O
when	O
the	O
program	O
was	O
ready	O
to	O
transfer	O
data	O
,	O
and	O
when	O
those	O
data	O
were	O
actually	O
arriving	O
at	O
the	O
drive	O
head	O
to	O
be	O
read	O
.	O
</s>
<s>
Interleaving	B-Application
was	O
common	O
prior	O
to	O
the	O
1990s	O
,	O
but	O
faded	O
from	O
use	O
as	O
processing	O
speeds	O
increased	O
.	O
</s>
<s>
Modern	O
operating	O
systems	O
do	O
not	O
use	O
interleaving	B-Application
for	O
,	O
e.g.	O
,	O
paging	B-Architecture
files	I-Architecture
.	O
</s>
<s>
Interleaving	B-Application
was	O
used	O
to	O
arrange	O
the	O
sectors	B-Application
most	O
efficiently	O
,	O
so	O
that	O
after	O
reading	O
a	O
sector	O
,	O
time	O
is	O
allowed	O
for	O
processing	O
,	O
and	O
then	O
the	O
next	O
sector	O
in	O
sequence	O
is	O
ready	O
to	O
be	O
read	O
just	O
as	O
the	O
computer	O
is	O
ready	O
to	O
do	O
so	O
.	O
</s>
<s>
Information	O
is	O
typically	O
stored	O
on	O
disks	O
in	O
small	O
pieces	O
referred	O
to	O
as	O
sectors	B-Application
or	O
blocks	O
.	O
</s>
<s>
When	O
data	O
was	O
read	O
,	O
the	O
reverse	O
process	O
transferred	O
data	O
first	O
into	O
the	O
buffer	O
and	O
then	O
to	O
system	O
RAM	B-Architecture
.	O
</s>
<s>
Most	O
early	O
computers	O
were	O
not	O
fast	O
enough	O
to	O
read	O
a	O
sector	O
,	O
move	O
the	O
data	O
from	O
the	O
buffer	O
to	O
system	O
RAM	B-Architecture
,	O
and	O
be	O
ready	O
to	O
read	O
the	O
next	O
sector	O
by	O
the	O
time	O
that	O
next	O
sector	O
was	O
appearing	O
under	O
the	O
read	O
head	O
.	O
</s>
<s>
If	O
sectors	B-Application
were	O
arranged	O
in	O
direct	O
order	O
,	O
after	O
the	O
first	O
sector	O
was	O
read	O
,	O
the	O
computer	O
might	O
,	O
for	O
example	O
,	O
have	O
sectors	B-Application
2	O
,	O
3	O
and	O
4	O
pass	O
under	O
the	O
read	O
head	O
before	O
it	O
was	O
ready	O
to	O
receive	O
data	O
again	O
.	O
</s>
<s>
The	O
computer	O
does	O
n't	O
need	O
sectors	B-Application
4	O
,	O
5	O
,	O
6	O
,	O
7	O
,	O
8	O
,	O
9	O
,	O
or	O
1	O
,	O
and	O
must	O
wait	O
for	O
them	O
to	O
pass	O
by	O
,	O
before	O
reading	O
sector	O
2	O
.	O
</s>
<s>
To	O
correct	O
for	O
the	O
processing	O
delays	O
,	O
the	O
ideal	O
interleave	O
for	O
this	O
system	O
would	O
be	O
1:4	O
,	O
ordering	O
the	O
sectors	B-Application
like	O
this	O
:	O
1	O
8	O
6	O
4	O
2	O
9	O
7	O
5	O
3	O
.	O
</s>
<s>
It	O
reads	O
sector	O
1	O
,	O
then	O
processes	O
it	O
while	O
the	O
three	O
sectors	B-Application
8	O
6	O
and	O
4	O
pass	O
by	O
,	O
and	O
when	O
the	O
microprocessor	O
becomes	O
ready	O
again	O
,	O
sector	O
two	O
is	O
arriving	O
just	O
as	O
it	O
is	O
needed	O
.	O
</s>
<s>
A	O
1:1	O
interleave	O
(	O
skip	B-Application
factor	I-Application
of	O
0	O
)	O
places	O
the	O
sectors	B-Application
sequentially	O
—	O
1	O
2	O
3	O
4	O
5	O
6	O
...	O
.	O
</s>
<s>
Modern	O
block	B-General_Concept
storage	I-General_Concept
devices	O
do	O
not	O
require	O
interleaving	B-Application
.	O
</s>
<s>
Data	O
is	O
now	O
commonly	O
stored	O
as	O
clusters	O
(	O
groups	O
of	O
sectors	B-Application
)	O
,	O
and	O
the	O
data	O
buffer	O
is	O
sufficiently	O
large	O
to	O
allow	O
all	O
sectors	B-Application
in	O
a	O
block	O
to	O
be	O
read	O
at	O
once	O
without	O
any	O
delay	O
between	O
sectors	B-Application
.	O
</s>
