<s>
A	O
virtual	B-Architecture
storage	I-Architecture
area	I-Architecture
network	I-Architecture
(	O
virtual	B-Architecture
SAN	I-Architecture
,	O
VSAN	O
or	O
vSAN	O
)	O
is	O
a	O
logical	O
representation	O
of	O
a	O
physical	O
storage	O
area	O
network	O
(	O
SAN	O
)	O
.	O
</s>
<s>
A	O
VSAN	O
abstracts	O
the	O
storage-related	O
operations	O
from	O
the	O
physical	O
storage	O
layer	O
,	O
and	O
provides	O
shared	O
storage	O
access	O
to	O
the	O
applications	O
and	O
virtual	B-Architecture
machines	I-Architecture
by	O
combining	O
the	O
servers	O
 '	O
local	O
storage	O
over	O
a	O
network	O
into	O
a	O
single	O
or	O
multiple	O
storage	O
pools	O
.	O
</s>
<s>
A	O
VSAN	O
operates	O
as	O
a	O
dedicated	O
piece	O
of	O
software	O
responsible	O
for	O
storage	O
access	O
,	O
and	O
depending	O
on	O
the	O
vendor	O
,	O
can	O
run	O
either	O
as	O
a	O
virtual	O
storage	O
appliance	O
(	O
VSA	O
)	O
,	O
a	O
storage	O
controller	O
that	O
runs	O
inside	O
an	O
isolated	O
virtual	B-Architecture
machine	I-Architecture
(	O
VM	O
)	O
or	O
as	O
an	O
ordinary	O
user-mode	O
application	O
,	O
such	O
as	O
StarWind	O
Virtual	B-Architecture
SAN	I-Architecture
,	O
or	O
DataCore	O
SANsymphony	O
.	O
</s>
<s>
Alternatively	O
it	O
can	O
be	O
implemented	O
as	O
a	O
kernel-mode	O
loadable	O
module	O
,	O
such	O
as	O
VMware	O
vSAN	O
,	O
Verge.io	O
virtual	B-Architecture
san	I-Architecture
(	O
VSAN	O
)	O
,	O
or	O
Microsoft	O
Storage	O
Spaces	O
Direct	O
(	O
S2D	O
)	O
.	O
</s>
<s>
For	O
sharing	O
storage	O
over	O
a	O
network	O
,	O
VSAN	O
utilizes	O
protocols	O
including	O
Fibre	B-Architecture
Channel	I-Architecture
(	O
FC	O
)	O
,	O
Internet	B-Protocol
Small	I-Protocol
Computer	I-Protocol
Systems	I-Protocol
Interface	I-Protocol
(	O
iSCSI	B-Protocol
)	O
,	O
Server	B-Operating_System
Message	I-Operating_System
Block	I-Operating_System
(	O
SMB	O
)	O
,	O
and	O
Network	B-Protocol
File	I-Protocol
System	I-Protocol
(	O
NFS	O
)	O
,	O
as	O
well	O
as	O
proprietary	O
protocols	O
.	O
</s>
<s>
A	O
VSAN	O
fills	O
a	O
similar	O
role	O
as	O
physical	O
SAN	O
infrastructure	O
,	O
but	O
is	O
also	O
used	O
for	O
workload	O
virtualization	O
which	O
can	O
include	O
databases	O
,	O
virtual	B-Protocol
desktop	I-Protocol
infrastructure	I-Protocol
(	O
VDI	O
)	O
environments	O
,	O
file	O
servers	O
,	O
CRM	O
systems	O
,	O
and	O
other	O
enterprise	O
applications	O
.	O
</s>
<s>
There	O
are	O
also	O
applications	O
with	O
DMZ	B-General_Concept
,	O
an	O
isolated	O
network	O
that	O
sits	O
outside	O
a	O
company	O
's	O
firewall	O
,	O
and	O
areas	O
with	O
space	O
constraints	O
,	O
such	O
as	O
vessels	O
,	O
where	O
a	O
reduced	O
hardware	O
footprint	O
2-3	O
node	O
deployment	O
has	O
a	O
better	O
chance	O
of	O
fitting	O
.	O
</s>
<s>
Using	O
a	O
VSAN	O
for	O
local	O
storage	O
provides	O
other	O
resiliency	O
options	O
including	O
mirroring	B-General_Concept
or	O
erasure	O
coding	O
with	O
different	O
parity	O
levels	O
.	O
</s>
<s>
A	O
VSAN	O
is	O
often	O
associated	O
with	O
hyperconvergence	B-Architecture
,	O
a	O
concept	O
which	O
refers	O
to	O
unifying	O
computing	O
,	O
networking	O
,	O
and	O
storage	O
resources	O
,	O
within	O
a	O
single	O
server	O
.	O
</s>
<s>
Similarly	O
,	O
a	O
VSAN	O
shifts	O
away	O
from	O
having	O
a	O
separate	O
physical	O
storage	O
layer	O
and	O
required	O
networking	B-Protocol
stack	I-Protocol
,	O
and	O
instead	O
combines	O
storage	O
from	O
multiple	O
nodes	O
into	O
a	O
virtualized	O
and	O
consolidated	O
storage	O
layer	O
.	O
</s>
<s>
VSANs	O
take	O
control	O
of	O
the	O
storage-related	O
operations	O
,	O
access	O
and	O
features	O
allowing	O
the	O
implementation	O
of	O
data	B-General_Concept
deduplication	I-General_Concept
,	O
data	B-General_Concept
compression	I-General_Concept
,	O
high	O
availability	O
and	O
other	O
features	O
,	O
on	O
commodity	O
x86	O
server	O
hardware	O
.	O
</s>
<s>
However	O
,	O
VSAN	O
can	O
be	O
also	O
used	O
in	O
converged	B-General_Concept
architectures	I-General_Concept
where	O
VSAN	O
is	O
deployed	O
on	O
dedicated	O
storage	O
nodes	O
as	O
a	O
cluster	O
,	O
and	O
presents	O
the	O
shared	O
storage	O
over	O
a	O
network	O
to	O
compute	O
nodes	O
.	O
</s>
