<s>
EnhanceIO	B-Application
is	O
a	O
disk	B-General_Concept
cache	I-General_Concept
module	O
for	O
the	O
Linux	O
kernel	O
.	O
</s>
<s>
Its	O
goal	O
is	O
to	O
use	O
fast	O
but	O
relatively	O
small	O
SSD	B-Device
drives	I-Device
to	O
improve	O
the	O
performance	O
of	O
large	O
but	O
slow	O
hard	B-Device
drives	I-Device
.	O
</s>
<s>
EnhanceIO	B-Application
makes	O
it	O
possible	O
to	O
add	O
an	O
SSD	B-Device
or	O
other	O
fast	O
disk	O
device	O
as	O
a	O
cache	B-General_Concept
to	O
another	O
block	O
device	O
,	O
such	O
as	O
a	O
hard	B-Device
drive	I-Device
,	O
in	O
order	O
to	O
improve	O
the	O
performance	O
of	O
the	O
disk	O
.	O
</s>
<s>
It	O
was	O
initially	O
based	O
on	O
Facebook	O
's	O
similar	O
Flashcache	B-Application
module	O
.	O
</s>
<s>
Unlike	O
Flashcache	B-Application
and	O
other	O
caching	B-General_Concept
solutions	O
,	O
it	O
does	O
n't	O
use	O
the	O
Linux	O
device	O
mapper	O
.	O
</s>
<s>
This	O
means	O
it	O
does	O
not	O
create	O
a	O
new	O
block	O
device	O
and	O
caching	B-General_Concept
can	O
be	O
added	O
to	O
existing	O
disks	O
,	O
without	O
reformatting	O
or	O
even	O
unmounting	O
them	O
.	O
</s>
<s>
This	O
makes	O
it	O
easy	O
to	O
add	O
cache	B-General_Concept
to	O
existing	O
systems	O
.	O
</s>
<s>
EnhanceIO	B-Application
was	O
first	O
announced	O
as	O
a	O
commercial	O
product	O
in	O
2011	O
by	O
sTec	O
Inc	O
,	O
a	O
company	O
specializing	O
in	O
SSD	B-Device
products	O
.	O
</s>
<s>
Late	O
2012	O
sTec	O
published	O
code	O
for	O
the	O
Linux	O
module	O
on	O
GitHub	B-Application
.	O
</s>
<s>
They	O
offered	O
the	O
EnhanceIO	B-Application
product	O
briefly	O
under	O
their	O
HGST	O
brand	O
.	O
</s>
<s>
As	O
the	O
project	O
was	O
abandoned	O
,	O
several	O
forks	O
were	O
created	O
with	O
some	O
patches	O
to	O
let	O
EnhanceIO	B-Application
work	O
on	O
later	O
kernels	O
.	O
</s>
