<s>
VM-aware	B-Application
storage	I-Application
(	O
VAS	O
)	O
is	O
computer	B-General_Concept
data	I-General_Concept
storage	I-General_Concept
designed	O
specifically	O
for	O
managing	O
storage	O
for	O
virtual	B-Architecture
machines	I-Architecture
(	O
VMs	O
)	O
within	O
a	O
data	B-Operating_System
center	I-Operating_System
.	O
</s>
<s>
VM-aware	B-Application
storage	I-Application
allows	O
storage	O
to	O
be	O
managed	O
as	O
an	O
integrated	O
part	O
of	O
managing	O
VMs	O
rather	O
than	O
as	O
logical	O
unit	O
numbers	O
(	O
LUNs	O
)	O
or	O
volumes	B-Application
that	O
are	O
separately	O
configured	O
and	O
managed	O
.	O
</s>
<s>
VM-aware	B-Application
storage	I-Application
is	O
often	O
used	O
in	O
conjunction	O
with	O
other	O
VM-aware	O
components	O
and	O
processes	O
such	O
as	O
VM-aware	O
computer	B-Architecture
network	I-Architecture
,	O
VM-aware	O
backup	B-Protocol
and	O
VM-aware	O
virus	B-Application
scanning	I-Application
.	O
</s>
<s>
VM-aware	B-Application
storage	I-Application
has	O
some	O
similarities	O
to	O
and	O
can	O
benefit	O
from	O
software-defined	O
networking	O
,	O
but	O
is	O
distinct	O
in	O
that	O
the	O
latter	O
provides	O
general	O
purpose	O
physical	O
equipment	O
that	O
can	O
be	O
customized	O
and	O
configured	O
in	O
software	O
whereas	O
VM-aware	B-Application
storage	I-Application
is	O
designed	O
for	O
virtual	B-Architecture
machines	I-Architecture
.	O
</s>
<s>
Adoption	O
of	O
server	B-Application
virtualization	B-General_Concept
technology	O
increased	O
rapidly	O
since	O
the	O
launch	O
of	O
the	O
VMware	B-Operating_System
ESX	I-Operating_System
hypervisor	B-Operating_System
in	O
2001	O
.	O
</s>
<s>
The	O
ability	O
to	O
consolidate	O
applications	O
running	O
on	O
tens	O
of	O
servers	O
in	O
a	O
single	O
physical	O
server	B-Application
running	O
a	O
hypervisor	B-Operating_System
resulted	O
in	O
cost	O
savings	O
for	O
servers	O
as	O
well	O
as	O
more	O
automated	O
management	O
of	O
the	O
servers	O
.	O
</s>
<s>
Due	O
to	O
these	O
advantages	O
,	O
by	O
early	O
2010	O
,	O
many	O
companies	O
had	O
implemented	O
"	O
virtualization	B-General_Concept
first	O
"	O
policies	O
,	O
which	O
stated	O
that	O
all	O
new	O
server	B-Application
deployments	O
should	O
be	O
virtual	O
unless	O
there	O
were	O
specific	O
reasons	O
to	O
use	O
a	O
physical	O
server	B-Application
.	O
</s>
<s>
As	O
virtualization	B-General_Concept
decreased	O
the	O
cost	O
of	O
the	O
server	B-Application
hardware	O
,	O
storage	O
began	O
to	O
dominate	O
the	O
cost	O
and	O
complexity	O
of	O
virtual	O
infrastructures	O
.	O
</s>
<s>
Server	B-Application
resources	O
were	O
often	O
managed	O
by	O
a	O
separate	O
team	O
than	O
the	O
storage	O
infrastructure	O
.	O
</s>
<s>
Initial	O
improvements	O
consisted	O
of	O
scripts	B-Language
and	O
plug-ins	B-Application
for	O
virtual	O
infrastructures	O
to	O
streamline	O
common	O
workflows	O
such	O
as	O
allocating	O
storage	O
for	O
VMs	O
.	O
</s>
<s>
Namely	O
,	O
virtual	O
infrastructure	O
is	O
designed	O
to	O
manage	O
VMs	O
while	O
storage	O
was	O
designed	O
to	O
manage	O
LUNs	O
and	O
volumes	B-Application
,	O
which	O
have	O
no	O
direct	O
relationship	O
with	O
VMs	O
.	O
</s>
<s>
Independently	O
of	O
VMware	O
,	O
several	O
startups	O
also	O
began	O
to	O
provide	O
VM-aware	B-Application
storage	I-Application
products	O
using	O
existing	O
virtual	O
infrastructure	O
management	O
interfaces	O
.	O
</s>
<s>
General-purpose	O
storage	B-General_Concept
systems	I-General_Concept
are	O
designed	O
around	O
storage	O
protocols	O
such	O
as	O
SCSI	B-Architecture
,	O
iSCSI	B-Protocol
,	O
Network	B-Protocol
File	I-Protocol
System	I-Protocol
(	O
NFS	O
)	O
and	O
server	B-Operating_System
message	I-Operating_System
block	I-Operating_System
(	O
SMB	O
)	O
which	O
were	O
created	O
before	O
the	O
advent	O
of	O
virtualization	B-General_Concept
.	O
</s>
<s>
As	O
a	O
result	O
,	O
their	O
fundamental	O
management	O
abstractions	O
are	O
LUNs	O
and	O
volumes	B-Application
,	O
which	O
have	O
little	O
to	O
do	O
with	O
the	O
VMs	O
.	O
</s>
<s>
General-purpose	O
storage	B-General_Concept
systems	I-General_Concept
are	O
configured	O
and	O
managed	O
mostly	O
independent	O
of	O
the	O
virtual	O
infrastructure	O
.	O
</s>
<s>
The	O
VM	O
abstractions	O
are	O
mapped	O
onto	O
the	O
storage	O
by	O
administrators	O
,	O
who	O
must	O
then	O
manage	O
this	O
mapping	O
and	O
create	O
policies	O
and	O
processes	O
for	O
translating	O
operations	O
on	O
VMs	O
into	O
corresponding	O
operations	O
on	O
LUNs	O
and	O
volumes	B-Application
.	O
</s>
<s>
For	O
example	O
,	O
because	O
there	O
are	O
no	O
standard	O
protocols	O
for	O
creating	O
and	O
destroying	O
LUNs	O
and	O
volumes	B-Application
,	O
most	O
virtual	O
infrastructures	O
store	O
many	O
VMs	O
on	O
a	O
single	O
LUN	O
or	O
volume	O
to	O
amortize	O
provisioning	O
and	O
management	O
overhead	O
.	O
</s>
<s>
Since	O
general-purpose	O
storage	B-General_Concept
systems	I-General_Concept
implement	O
most	O
storage-management	O
functionality	O
such	O
as	O
monitoring	O
,	O
snapshots	B-Application
,	O
cloning	O
,	O
replication	B-Architecture
and	O
QoS	O
on	O
LUNs	O
and	O
volumes	B-Application
rather	O
than	O
VMs	O
and	O
virtual	O
disks	O
,	O
this	O
means	O
storage	B-General_Concept
systems	I-General_Concept
lose	O
the	O
ability	O
to	O
perform	O
these	O
operations	O
on	O
individual	O
VMs	O
.	O
</s>
<s>
In	O
contrast	O
,	O
VM-aware	B-Application
storage	I-Application
is	O
designed	O
around	O
VMs	O
.	O
</s>
