<s>
In	O
computing	O
,	O
a	O
Parallel	B-Operating_System
Sysplex	I-Operating_System
is	O
a	O
cluster	B-Architecture
of	O
IBM	B-Device
mainframes	I-Device
acting	O
together	O
as	O
a	O
single	B-Operating_System
system	I-Operating_System
image	I-Operating_System
with	O
z/OS	B-Application
.	O
</s>
<s>
Used	O
for	O
disaster	O
recovery	O
,	O
Parallel	B-Operating_System
Sysplex	I-Operating_System
combines	O
data	O
sharing	O
and	O
parallel	B-Operating_System
computing	I-Operating_System
to	O
allow	O
a	O
cluster	B-Architecture
of	O
up	O
to	O
32	O
systems	O
to	O
share	O
a	O
workload	O
for	O
high	B-Architecture
performance	I-Architecture
and	O
high	O
availability	O
.	O
</s>
<s>
In	O
1990	O
,	O
IBM	B-Device
mainframe	I-Device
computers	O
introduced	O
the	O
concept	O
of	O
a	O
Systems	O
Complex	O
,	O
commonly	O
called	O
a	O
Sysplex	O
,	O
with	O
MVS/ESA	O
SPV4.1	O
.	O
</s>
<s>
This	O
allows	O
authorized	O
components	O
in	O
up	O
to	O
eight	O
logical	B-Device
partitions	I-Device
(	O
LPARs	B-Device
)	O
to	O
communicate	O
and	O
cooperate	O
with	O
each	O
other	O
using	O
the	O
XCF	B-Application
protocol	O
.	O
</s>
<s>
CICS	B-Application
–	O
uses	O
XCF	B-Application
to	O
provide	O
better	O
performance	O
and	O
response	O
time	O
than	O
using	O
VTAM	O
for	O
transaction	O
routing	O
and	O
function	O
shipping	O
.	O
</s>
<s>
IBM	O
introduced	O
the	O
Parallel	B-Operating_System
Sysplex	I-Operating_System
with	O
the	O
addition	O
of	O
the	O
9674	O
Coupling	B-Device
Facility	I-Device
(	O
CF	O
)	O
,	O
new	O
S/390	O
models	O
,	O
upgrades	O
to	O
existing	O
models	O
,	O
coupling	O
links	O
for	O
high	O
speed	O
communication	O
and	O
MVS/ESA	O
SP	O
V5.1	O
operating	B-General_Concept
system	I-General_Concept
support	O
,	O
in	O
April	O
1994	O
.	O
</s>
<s>
The	O
Coupling	B-Device
Facility	I-Device
(	O
CF	O
)	O
may	O
reside	O
on	O
a	O
dedicated	O
stand-alone	O
server	O
configured	O
with	O
processors	O
that	O
can	O
run	O
Coupling	B-Device
Facility	I-Device
control	O
code	O
(	O
CFCC	O
)	O
,	O
as	O
integral	O
processors	O
on	O
the	O
mainframes	B-Architecture
themselves	O
configured	O
as	O
ICFs	O
(	O
Internal	O
Coupling	B-Device
Facilities	I-Device
)	O
,	O
or	O
less	O
common	O
,	O
as	O
normal	O
LPARs	B-Device
.	O
</s>
<s>
The	O
CF	O
contains	O
Lock	O
,	O
List	O
,	O
and	O
Cache	O
structures	O
to	O
help	O
with	O
serialization	O
,	O
message	O
passing	O
,	O
and	O
buffer	O
consistency	O
between	O
multiple	O
LPARs	B-Device
.	O
</s>
<s>
The	O
primary	O
goal	O
of	O
a	O
Parallel	B-Operating_System
Sysplex	I-Operating_System
is	O
to	O
provide	O
data	O
sharing	O
capabilities	O
,	O
allowing	O
multiple	O
databases	O
for	O
direct	O
reads	O
and	O
writes	O
to	O
shared	O
data	O
.	O
</s>
<s>
Databases	O
running	O
on	O
the	O
System	B-Device
z	I-Device
server	O
that	O
can	O
take	O
advantage	O
of	O
this	O
include	O
:	O
</s>
<s>
IBM	B-Application
Information	I-Application
Management	I-Application
System	I-Application
(	O
IMS	O
)	O
.	O
</s>
<s>
Other	O
components	O
can	O
use	O
the	O
Coupling	B-Device
Facility	I-Device
to	O
help	O
with	O
system	O
management	O
,	O
performance	O
,	O
or	O
reduced	O
hardware	O
requirements	O
.	O
</s>
<s>
Tape	O
Switching	O
uses	O
the	O
GRS	O
structure	O
to	O
provide	O
sharing	O
of	O
tape	O
units	O
between	O
z/OS	B-Application
images	O
.	O
</s>
<s>
WLM	O
-	O
provides	O
support	O
for	O
Intelligent	O
Resource	O
Director	O
(	O
IRD	O
)	O
to	O
extends	O
the	O
z/OS	B-Application
Workload	B-Application
Manager	I-Application
to	O
help	O
manage	O
CPU	O
and	O
I/O	O
resources	O
across	O
multiple	O
LPARs	B-Device
within	O
the	O
Parallel	B-Operating_System
Sysplex	I-Operating_System
.	O
</s>
<s>
Functions	O
include	O
LPAR	B-Device
CPU	O
management	O
,	O
IRD	O
.	O
</s>
<s>
Major	O
components	O
of	O
a	O
Parallel	B-Operating_System
Sysplex	I-Operating_System
include	O
:	O
</s>
<s>
Coupling	B-Device
Facility	I-Device
(	O
CF	O
or	O
ICF	O
)	O
hardware	O
,	O
allowing	O
multiple	O
processors	O
to	O
share	O
,	O
cache	O
,	O
update	O
,	O
and	O
balance	O
data	O
access	O
;	O
</s>
<s>
Software	O
(	O
operating	B-General_Concept
system	I-General_Concept
services	O
and	O
,	O
usually	O
,	O
middleware	B-General_Concept
such	O
as	O
IBM	B-Application
Db2	I-Application
)	O
.	O
</s>
<s>
The	O
Coupling	B-Device
Facility	I-Device
may	O
be	O
either	O
a	O
dedicated	O
external	O
system	O
(	O
a	O
small	O
mainframe	B-Architecture
,	O
such	O
as	O
a	O
System	B-Device
z9	I-Device
BC	O
,	O
specially	O
configured	O
with	O
only	O
coupling	B-Device
facility	I-Device
processors	O
)	O
or	O
integral	O
processors	O
on	O
the	O
mainframes	B-Architecture
themselves	O
configured	O
as	O
ICFs	O
(	O
Internal	O
Coupling	B-Device
Facilities	I-Device
)	O
.	O
</s>
<s>
It	O
is	O
recommended	O
that	O
at	O
least	O
one	O
external	O
CF	O
be	O
used	O
in	O
a	O
parallel	B-Operating_System
sysplex	I-Operating_System
.	O
</s>
<s>
It	O
is	O
recommended	O
that	O
a	O
Parallel	B-Operating_System
Sysplex	I-Operating_System
has	O
at	O
least	O
two	O
CFs	O
and/or	O
ICFs	O
for	O
redundancy	O
,	O
especially	O
in	O
a	O
production	O
data	O
sharing	O
environment	O
.	O
</s>
<s>
Server	O
Time	O
Protocol	O
(	O
STP	O
)	O
replaced	O
the	O
Sysplex	O
Timers	O
beginning	O
in	O
2005	O
for	O
System	B-Device
z	I-Device
mainframe	B-Architecture
models	O
z990	O
and	O
newer	O
.	O
</s>
<s>
A	O
Sysplex	O
Timer	O
is	O
a	O
physically	O
separate	O
piece	O
of	O
hardware	O
from	O
the	O
mainframe	B-Architecture
,	O
whereas	O
STP	O
is	O
an	O
integral	O
facility	O
within	O
the	O
mainframe	B-Architecture
's	O
microcode	O
.	O
</s>
<s>
With	O
STP	O
and	O
ICFs	O
it	O
is	O
possible	O
to	O
construct	O
a	O
complete	O
Parallel	B-Operating_System
Sysplex	I-Operating_System
installation	O
with	O
two	O
connected	O
mainframes	B-Architecture
.	O
</s>
<s>
Moreover	O
,	O
a	O
single	O
mainframe	B-Architecture
can	O
contain	O
the	O
internal	O
equivalent	O
of	O
a	O
complete	O
physical	O
Parallel	B-Operating_System
Sysplex	I-Operating_System
,	O
useful	O
for	O
application	O
testing	O
and	O
development	O
purposes	O
.	O
</s>
<s>
Based	O
on	O
Network	O
Time	O
Protocol	O
concepts	O
,	O
one	O
of	O
the	O
System	B-Device
z	I-Device
servers	O
is	O
designated	O
by	O
the	O
HMC	O
as	O
the	O
primary	O
time	O
source	O
(	O
Stratum	O
1	O
)	O
.	O
</s>
<s>
STP	O
has	O
been	O
available	O
on	O
System	B-Device
z	I-Device
servers	O
since	O
2005	O
.	O
</s>
<s>
Geographically	O
Dispersed	O
Parallel	B-Operating_System
Sysplex	I-Operating_System
(	O
GDPS	O
)	O
is	O
an	O
extension	O
of	O
Parallel	B-Operating_System
Sysplex	I-Operating_System
of	O
mainframes	B-Architecture
located	O
,	O
potentially	O
,	O
in	O
different	O
cities	O
.	O
</s>
<s>
GDPS	O
HyperSwap	O
Manager	O
:	O
This	O
is	O
based	O
on	O
synchronous	O
Peer	B-Device
to	I-Device
Peer	I-Device
Remote	I-Device
Copy	I-Device
(	O
PPRC	O
)	O
technology	O
for	O
use	O
within	O
a	O
single	O
data	O
center	O
.	O
</s>
<s>
GDPS	O
Metro	O
:	O
This	O
is	O
based	O
on	O
synchronous	O
data	O
mirroring	O
technology	O
(	O
PPRC	O
)	O
that	O
can	O
be	O
used	O
on	O
mainframes	B-Architecture
apart	O
.	O
</s>
<s>
GDPS	O
Global	O
-	O
XRC	O
:	O
This	O
is	O
based	O
on	O
asynchronous	O
Extended	B-Device
Remote	I-Device
Copy	I-Device
(	O
XRC	O
)	O
technology	O
with	O
no	O
restrictions	O
on	O
distance	O
.	O
</s>
<s>
GDPS	O
Global	O
-	O
GM	O
:	O
This	O
is	O
based	O
on	O
asynchronous	O
IBM	B-Application
Global	I-Application
Mirror	I-Application
technology	O
with	O
no	O
restrictions	O
on	O
distance	O
.	O
</s>
