<s>
Veritas	B-Operating_System
Cluster	I-Operating_System
Server	I-Operating_System
(	O
rebranded	O
as	O
Veritas	O
Infoscale	O
Availability	O
and	O
also	O
known	O
as	O
VCS	O
and	O
also	O
sold	O
bundled	O
in	O
the	O
SFHA	O
product	O
)	O
is	O
a	O
high-availability	B-General_Concept
cluster	I-General_Concept
software	O
for	O
Unix	B-Application
,	O
Linux	B-Application
and	O
Microsoft	B-Application
Windows	I-Application
computer	O
systems	O
,	O
created	O
by	O
Veritas	O
Technologies	O
.	O
</s>
<s>
High-availability	B-General_Concept
clusters	I-General_Concept
(	O
HAC	O
)	O
improve	O
application	O
availability	O
by	O
failing	O
or	O
switching	O
them	O
over	O
in	O
a	O
group	O
of	O
systems	O
—	O
as	O
opposed	O
to	O
high-performance	B-Architecture
clusters	I-Architecture
,	O
which	O
improve	O
application	O
performance	O
by	O
running	O
them	O
on	O
multiple	O
systems	O
simultaneously	O
.	O
</s>
<s>
Most	O
Veritas	B-Operating_System
Cluster	I-Operating_System
Server	I-Operating_System
implementations	O
attempt	O
to	O
build	O
availability	O
into	O
a	O
cluster	O
,	O
eliminating	O
single	O
points	O
of	O
failure	O
by	O
making	O
use	O
of	O
redundant	O
components	O
like	O
multiple	O
network	O
cards	O
,	O
storage	O
area	O
networks	O
in	O
addition	O
to	O
the	O
use	O
of	O
VCS	O
.	O
</s>
<s>
Similar	O
products	O
include	O
Fujitsu	O
PRIMECLUSTER	O
,	O
IBM	B-Operating_System
PowerHA	I-Operating_System
System	I-Operating_System
Mirror	I-Operating_System
,	O
HP	B-Application
ServiceGuard	I-Application
,	O
IBM	O
Tivoli	O
System	O
Automation	O
for	O
Multiplatforms	O
(	O
SA	O
MP	O
)	O
,	O
Linux-HA	B-Operating_System
,	O
OpenSAF	B-General_Concept
,	O
Microsoft	B-Operating_System
Cluster	I-Operating_System
Server	I-Operating_System
(	O
MSCS	B-Operating_System
)	O
,	O
NEC	O
ExpressCluster	O
,	O
Red	B-Operating_System
Hat	I-Operating_System
Cluster	I-Operating_System
Suite	I-Operating_System
,	O
SteelEye	B-Operating_System
LifeKeeper	I-Operating_System
and	O
Sun	B-Operating_System
Cluster	I-Operating_System
.	O
</s>
<s>
VCS	O
is	O
one	O
of	O
the	O
few	O
products	O
in	O
the	O
industry	O
that	O
provides	O
both	O
high	O
availability	O
and	O
disaster	O
recovery	O
across	O
all	O
major	O
operating	B-General_Concept
systems	I-General_Concept
while	O
supporting	O
40+	O
major	O
application/replication	O
technologies	O
out	O
of	O
the	O
box	O
.	O
</s>
<s>
VCS	O
is	O
mostly	O
a	O
user-level	O
clustering	O
software	O
;	O
most	O
of	O
its	O
processes	O
are	O
normal	O
system	O
processes	O
on	O
the	O
systems	O
it	O
operates	O
on	O
,	O
and	O
have	O
no	O
special	O
access	O
to	O
the	O
operating	B-General_Concept
system	I-General_Concept
or	O
kernel	B-Operating_System
functions	O
in	O
the	O
host	O
systems	O
.	O
</s>
<s>
However	O
,	O
the	O
interconnect	O
(	O
heartbeat	B-Operating_System
)	O
technology	O
used	O
with	O
VCS	O
is	O
a	O
proprietary	O
Layer	B-Protocol
2	I-Protocol
ethernet-based	O
protocol	O
that	O
is	O
run	O
in	O
the	O
kernel	B-Operating_System
space	O
using	O
kernel	B-Operating_System
modules	O
.	O
</s>
<s>
The	O
group	O
membership	O
protocol	O
that	O
runs	O
on	O
top	O
of	O
the	O
interconnect	O
heartbeat	B-Operating_System
protocol	O
is	O
also	O
implemented	O
in	O
the	O
kernel	B-Operating_System
.	O
</s>
<s>
In	O
case	O
of	O
a	O
split	B-General_Concept
brain	I-General_Concept
,	O
the	O
'	O
fencing	O
 '	O
module	O
does	O
the	O
work	O
of	O
arbitration	O
and	O
data	O
protection	O
.	O
</s>
<s>
Fencing	O
too	O
is	O
implemented	O
as	O
a	O
kernel	B-Operating_System
module	O
.	O
</s>
<s>
Veritas	B-Operating_System
Cluster	I-Operating_System
Server	I-Operating_System
for	O
Windows	O
is	O
available	O
as	O
a	O
standalone	O
product	O
.	O
</s>
<s>
It	O
is	O
also	O
sold	O
bundled	O
with	O
Storage	B-Application
Foundation	I-Application
as	O
Storage	B-Application
Foundation	I-Application
HA	O
for	O
Windows	O
;	O
Veritas	B-Operating_System
Cluster	I-Operating_System
Server	I-Operating_System
for	O
AIX	O
,	O
HP-UX	O
,	O
Linux	B-Application
,	O
and	O
Solaris	O
is	O
supplied	O
as	O
a	O
standalone	O
product	O
.	O
</s>
<s>
The	O
Veritas	B-Operating_System
Cluster	I-Operating_System
Server	I-Operating_System
product	O
includes	O
,	O
a	O
multi-cluster	O
management	O
software	O
that	O
automates	O
disaster	O
recovery	O
across	O
data	O
centers	O
.	O
</s>
