<s>
SanDisk/Fusion	O
-io	O
'	O
s	O
NVMFS	B-Application
file	B-Application
system	I-Application
,	O
formerly	O
known	O
as	O
Direct	O
File	B-Application
System	I-Application
(	O
DFS	O
)	O
,	O
accesses	O
flash	B-Device
memory	I-Device
via	O
a	O
virtual	O
flash	B-Device
storage	I-Device
layer	O
instead	O
of	O
using	O
the	O
traditional	O
block	O
layer	O
API	O
.	O
</s>
<s>
This	O
file	B-Application
system	I-Application
has	O
two	O
main	O
novel	O
features	O
.	O
</s>
<s>
Second	O
,	O
it	O
leverages	O
the	O
virtual	O
flash	B-Device
storage	I-Device
layer	O
to	O
perform	O
block	O
allocations	O
and	O
atomic	O
updates	O
.	O
</s>
<s>
As	O
a	O
result	O
,	O
NVMFS	B-Application
performs	O
better	O
and	O
is	O
much	O
simpler	O
than	O
a	O
traditional	O
Unix	O
file	B-Application
system	I-Application
with	O
similar	O
functionalities	O
.	O
</s>
<s>
Additionally	O
,	O
this	O
approach	O
avoids	O
the	O
log-on-log	O
performance	O
issues	O
triggered	O
by	O
log-structured	B-Application
file	I-Application
systems	I-Application
.	O
</s>
<s>
Microbenchmark	O
results	O
show	O
that	O
NVMFS	B-Application
can	O
deliver	O
94,000	O
I/O	O
operations	O
per	O
second	O
(	O
IOPS	O
)	O
for	O
direct	O
reads	O
and	O
71,000	O
IOPS	O
for	O
direct	O
writes	O
with	O
the	O
virtualized	O
flash	B-Device
storage	I-Device
layer	O
on	O
top	O
of	O
a	O
first-generation	O
Fusion-io	O
ioDrive	O
.	O
</s>
<s>
For	O
direct	O
access	O
performance	O
,	O
NVMFS	B-Application
is	O
consistently	O
better	O
than	O
ext3	B-Application
on	O
the	O
same	O
platform	O
,	O
sometimes	O
by	O
20%	O
.	O
</s>
<s>
For	O
buffered	O
access	O
performance	O
,	O
NVMFS	B-Application
is	O
also	O
consistently	O
better	O
than	O
ext3	B-Application
,	O
and	O
sometimes	O
by	O
over	O
149%	O
.	O
</s>
<s>
Application	O
benchmarks	O
show	O
that	O
NVMFS	B-Application
outperforms	O
ext3	B-Application
by	O
7%	O
to	O
250%	O
while	O
requiring	O
less	O
CPU	O
power	O
.	O
</s>
<s>
Additionally	O
,	O
I/O	O
latency	O
is	O
lower	O
with	O
NVMFS	B-Application
compared	O
to	O
ext3	B-Application
.	O
</s>
<s>
The	O
API	O
used	O
by	O
NVMFS	B-Application
to	O
access	O
flash	B-Device
memory	I-Device
consists	O
of	O
:	O
</s>
<s>
An	O
address	O
space	O
that	O
is	O
several	O
orders	O
of	O
magnitude	O
larger	O
than	O
the	O
storage	O
capacity	O
of	O
the	O
flash	B-Device
memory	I-Device
.	O
</s>
<s>
The	O
layer	O
that	O
provides	O
this	O
API	O
is	O
called	O
the	O
virtualized	O
flash	B-Device
storage	I-Device
layer	O
in	O
the	O
DFS	O
paper	O
.	O
</s>
<s>
It	O
is	O
the	O
responsibility	O
of	O
this	O
layer	O
to	O
perform	O
block	O
allocation	O
,	O
wear	B-Application
leveling	I-Application
,	O
garbage	B-General_Concept
collection	I-General_Concept
,	O
crash	O
recovery	O
,	O
address	O
translation	O
and	O
also	O
to	O
make	O
the	O
address	O
translation	O
data	O
structures	O
persistent	O
.	O
</s>
