<s>
A	O
logical	B-Device
partition	I-Device
(	O
LPAR	B-Device
)	O
is	O
a	O
subset	O
of	O
a	O
computer	O
's	O
hardware	O
resources	O
,	O
virtualized	B-General_Concept
as	O
a	O
separate	O
computer	O
.	O
</s>
<s>
In	O
effect	O
,	O
a	O
physical	O
machine	O
can	O
be	O
partitioned	O
into	O
multiple	O
logical	B-Device
partitions	I-Device
,	O
each	O
hosting	O
a	O
separate	O
instance	O
of	O
an	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
Although	O
the	O
terms	O
PR/SM	B-Device
and	O
LPAR	B-Device
are	O
often	O
used	O
interchangeably	O
in	O
IBM	B-Device
Z	I-Device
,	O
including	O
in	O
IBM	O
documentation	O
,	O
PR/SM	B-Device
was	O
not	O
present	O
in	O
the	O
IBM	B-Device
System/370	I-Device
Model	I-Device
168	I-Device
's	O
Virtual	B-Application
Machine	I-Application
Facility/370	I-Application
;	O
it	O
came	O
in	O
with	O
the	O
IBM	B-Device
3090	I-Device
,	O
years	O
later	O
.	O
</s>
<s>
Formally	O
,	O
LPAR	B-Device
designates	O
the	O
mode	O
of	O
operation	O
or	O
an	O
individual	O
logical	B-Device
partition	I-Device
,	O
whereas	O
PR/SM	B-Device
is	O
the	O
commercial	O
designation	O
of	O
the	O
feature	O
.	O
</s>
<s>
In	O
mainframe	O
computing	O
PR/SM	B-Device
(	O
Processor	B-Device
Resource/System	I-Device
Manager	I-Device
)	O
is	O
a	O
type-1	O
Hypervisor	B-Operating_System
(	O
a	O
virtual	B-Operating_System
machine	I-Operating_System
monitor	I-Operating_System
)	O
that	O
allows	O
multiple	O
logical	B-Device
partitions	I-Device
to	O
share	O
physical	O
resources	O
such	O
as	O
CPUs	B-Device
,	O
I/O	B-Device
channels	I-Device
and	O
LAN	O
interfaces	O
;	O
when	O
sharing	O
channels	O
,	O
the	O
LPARs	B-Device
can	O
share	O
I/O	O
devices	O
such	O
as	O
direct	B-Application
access	I-Application
storage	I-Application
devices	I-Application
(	O
DASD	B-Application
)	O
.	O
</s>
<s>
PR/SM	B-Device
is	O
integrated	O
with	O
all	O
IBM	B-Device
System	I-Device
z	I-Device
machines	O
.	O
</s>
<s>
Similar	O
facilities	O
exist	O
on	O
the	O
IBM	B-Device
Power	I-Device
Systems	I-Device
family	O
,	O
and	O
its	O
predecessors	O
.	O
</s>
<s>
IBM	O
introduced	O
PR/SM	B-Device
in	O
1988	O
with	O
the	O
IBM	B-Device
3090	I-Device
processors	O
.	O
</s>
<s>
IBM	O
developed	O
the	O
concept	O
of	O
hypervisors	B-Operating_System
in	O
their	O
CP-40	B-Application
and	O
CP-67	B-Application
,	O
and	O
in	O
1972	O
provided	O
it	O
for	O
the	O
S/370	B-Device
as	O
Virtual	B-Application
Machine	I-Application
Facility/370	I-Application
.	O
</s>
<s>
IBM	O
introduced	O
the	O
Start	O
Interpretive	O
Execution	O
(	O
SIE	O
)	O
instruction	O
as	O
part	O
of	O
370-XA	O
on	O
the	O
3081	O
,	O
and	O
VM/XA	B-Application
versions	O
of	O
VM	B-Application
to	O
exploit	O
it	O
.	O
</s>
<s>
PR/SM	B-Device
is	O
a	O
type-1	O
Hypervisor	B-Operating_System
based	O
on	O
the	O
CP	O
component	O
of	O
VM/XA	B-Application
that	O
runs	O
directly	O
on	O
the	O
machine	O
level	O
and	O
allocates	O
system	O
resources	O
across	O
LPARs	B-Device
to	O
share	O
physical	O
resources	O
.	O
</s>
<s>
It	O
is	O
a	O
standard	O
feature	O
on	O
IBM	B-Device
Z	I-Device
and	O
IBM	B-Application
LinuxONE	I-Application
machines	O
.	O
</s>
<s>
IBM	O
introduced	O
a	O
related	O
,	O
simplified	O
,	O
optional	O
feature	O
called	O
Dynamic	O
Partition	B-Device
Manager	O
(	O
DPM	O
)	O
on	O
its	O
IBM	O
z13	O
and	O
first	O
generation	O
IBM	B-Application
LinuxONE	I-Application
machines	O
.	O
</s>
<s>
DPM	O
provides	O
Web-based	O
user	O
interfaces	O
for	O
many	O
LPAR-related	O
configuration	O
and	O
monitoring	O
tasks	O
.	O
</s>
<s>
IBM	O
developed	O
the	O
concept	O
of	O
hypervisors	B-Operating_System
(	O
virtual	B-Architecture
machines	I-Architecture
in	O
CP-40	B-Application
and	O
CP-67	B-Application
)	O
and	O
in	O
1972	O
provided	O
it	O
for	O
the	O
S/370	B-Device
as	O
Virtual	B-Application
Machine	I-Application
Facility/370	I-Application
.	O
</s>
<s>
IBM	O
introduced	O
the	O
Start	O
Interpretive	O
Execution	O
(	O
SIE	O
)	O
instruction	O
(	O
designed	O
specifically	O
for	O
the	O
execution	O
of	O
virtual	B-Architecture
machines	I-Architecture
)	O
as	O
part	O
of	O
370-XA	O
architecture	O
on	O
the	O
3081	O
,	O
as	O
well	O
as	O
VM/XA	B-Application
versions	O
of	O
VM	B-Application
to	O
exploit	O
it	O
.	O
</s>
<s>
PR/SM	B-Device
is	O
a	O
type-1	O
Hypervisor	B-Operating_System
based	O
on	O
the	O
CP	O
component	O
of	O
VM/XA	B-Application
that	O
runs	O
directly	O
on	O
the	O
machine	O
level	O
and	O
allocates	O
system	O
resources	O
across	O
LPARs	B-Device
to	O
share	O
physical	O
resources	O
.	O
</s>
<s>
It	O
is	O
a	O
standard	O
feature	O
on	O
IBM	B-Device
System	I-Device
z	I-Device
only	O
.	O
</s>
<s>
An	O
IBM	B-Device
POWER	I-Device
system	I-Device
uses	O
PHYP	O
(	O
the	O
POWER	O
Hypervisor	B-Operating_System
)	O
to	O
enable	O
its	O
LPAR	B-Device
functionalities	O
for	O
System	O
p	O
and	O
System	O
i	O
since	O
approximately	O
2000	O
in	O
POWER4	O
systems	O
.	O
</s>
<s>
IBM	O
began	O
marketing	O
its	O
functionally	O
similar	O
PR/SM	B-Device
in	O
1988	O
,	O
implemented	O
on	O
its	O
ESA/390	O
architecture	O
released	O
that	O
year	O
.	O
</s>
<s>
MDF-based	O
LPAR	B-Device
technology	O
continued	O
to	O
be	O
developed	O
separately	O
by	O
Amdahl	O
,	O
and	O
Hitachi	O
Data	O
Systems	O
in	O
part	O
for	O
their	O
implementations	O
of	O
the	O
new	O
architecture	O
,	O
which	O
featured	O
the	O
introduction	O
of	O
access	B-Application
registers	I-Application
that	O
allowed	O
use	O
of	O
multiple	O
data	B-Application
spaces	I-Application
addressable	O
by	O
a	O
single	O
address	B-General_Concept
space	I-General_Concept
.	O
</s>
<s>
IBM	O
subsequently	O
continued	O
its	O
LPAR	B-Device
development	O
with	O
its	O
64-bit	O
System	B-Device
z	I-Device
and	O
IBM	B-Device
AS/400	I-Device
architectures	O
.	O
</s>
<s>
LPAR	B-Device
and	O
PR/SM	B-Device
reconfigurations	O
can	O
be	O
made	O
without	O
rebooting	O
the	O
computer	O
,	O
i.e.	O
,	O
while	O
some	O
LPARs	B-Device
remain	O
active	O
.	O
</s>
<s>
z/VM	B-Application
supports	O
the	O
z/Architecture	O
HiperSockets	B-Device
function	O
for	O
high-speed	O
TCP/IP	B-Protocol
communication	O
among	O
virtual	B-Architecture
machines	I-Architecture
and	O
logical	B-Device
partitions	I-Device
(	O
LPARs	B-Device
)	O
within	O
the	O
same	O
IBM	O
zSeries	O
server	O
.	O
</s>
<s>
IBM	O
later	O
introduced	O
LPARs	B-Device
to	O
their	O
iSeries	B-Application
and	O
pSeries	O
servers	O
in	O
1999	O
and	O
2001	O
,	O
respectively	O
,	O
albeit	O
with	O
varying	O
technical	O
specifications	O
.	O
</s>
<s>
Multiple	O
operating	B-General_Concept
systems	I-General_Concept
are	O
compatible	O
with	O
LPARs	B-Device
,	O
including	O
z/OS	B-Application
,	O
z/VM	B-Application
,	O
z/VSE	B-Application
,	O
z/TPF	B-Operating_System
,	O
AIX	B-Application
,	O
Linux	B-Application
,	O
and	O
IBM	B-Application
i	I-Application
.	O
</s>
<s>
In	O
storage	B-General_Concept
systems	I-General_Concept
,	O
such	O
as	O
the	O
IBM	O
TotalStorage	O
DS8000	O
,	O
LPARs	B-Device
allow	O
for	O
multiple	O
virtual	O
instances	O
of	O
a	O
storage	B-General_Concept
array	I-General_Concept
to	O
exist	O
within	O
a	O
single	O
physical	O
array	O
.	O
</s>
<s>
In	O
early	O
2010	O
Fujitsu	O
announced	O
availability	O
of	O
its	O
x86-64	B-Device
PRIMEQUEST	O
line	O
of	O
servers	O
,	O
which	O
support	O
LPARs	B-Device
.	O
</s>
<s>
In	O
late	O
2011	O
,	O
Hitachi	O
announced	O
availability	O
of	O
CB2000	O
and	O
CB320	O
blade	O
systems	O
,	O
which	O
support	O
LPAR	B-Device
on	O
x86-64	B-Device
hardware	O
.	O
</s>
<s>
Logical	B-Device
partitioning	I-Device
divides	O
hardware	O
resources	O
.	O
</s>
<s>
Two	O
LPARs	B-Device
may	O
access	O
memory	B-General_Concept
from	O
a	O
common	O
memory	B-General_Concept
chip	O
,	O
provided	O
that	O
the	O
ranges	O
of	O
addresses	O
directly	O
accessible	O
to	O
each	O
do	O
not	O
overlap	O
.	O
</s>
<s>
It	O
is	O
possible	O
for	O
one	O
partition	B-Device
to	O
control	O
memory	B-General_Concept
managed	O
by	O
a	O
second	O
partition	B-Device
indirectly	O
by	O
communicating	O
with	O
a	O
process	O
on	O
the	O
partition	B-Device
with	O
direct	O
access	O
,	O
which	O
acts	O
as	O
an	O
intermediary	O
.	O
</s>
<s>
CPUs	B-Device
may	O
be	O
dedicated	O
to	O
a	O
single	O
LPAR	B-Device
or	O
shared	O
.	O
</s>
<s>
While	O
on	O
Amdahl	O
's	O
MDF	O
(	O
Multiple	O
Domain	O
Facility	O
)	O
it	O
was	O
possible	O
to	O
configure	O
an	O
LPAR	B-Device
with	O
both	O
shared	O
and	O
dedicated	O
CPUs	B-Device
,	O
this	O
is	O
no	O
longer	O
possible	O
with	O
any	O
mainframes	O
currently	O
in	O
the	O
market	O
.	O
</s>
<s>
On	O
IBM	O
mainframes	O
,	O
LPARs	B-Device
are	O
managed	O
by	O
the	O
PR/SM	B-Device
facility	O
or	O
a	O
related	O
,	O
optional	O
,	O
simplified	O
facility	O
called	O
Dynamic	O
Partition	B-Device
Manager	O
(	O
DPM	O
)	O
.	O
</s>
<s>
All	O
64-bit	O
IBM	O
mainframes	O
,	O
except	O
for	O
the	O
first	O
generation	O
64-bit	O
models	O
(	O
z900	O
and	O
z800	O
)	O
,	O
operate	O
exclusively	O
in	O
LPAR	B-Device
mode	O
,	O
even	O
when	O
there	O
is	O
only	O
one	O
partition	B-Device
on	O
a	O
machine	O
.	O
</s>
<s>
Multiple	O
LPARs	B-Device
running	O
z/OS	B-Application
can	O
form	O
a	O
Sysplex	O
or	O
Parallel	B-Operating_System
Sysplex	I-Operating_System
,	O
whether	O
on	O
one	O
machine	O
or	O
spread	O
across	O
multiple	O
machines	O
.	O
</s>
<s>
On	O
IBM	O
System	O
p	O
POWER	B-Device
hardware	I-Device
,	O
LPARs	B-Device
are	O
managed	O
by	O
PHYP	O
(	O
the	O
POWER	O
Hypervisor	B-Operating_System
)	O
.	O
</s>
<s>
PHYP	O
acts	O
as	O
a	O
virtual	O
switch	O
between	O
the	O
LPARs	B-Device
and	O
also	O
handles	O
the	O
virtual	O
SCSI	B-Architecture
traffic	O
between	O
LPARs	B-Device
.	O
</s>
<s>
Micro-Partitioning	B-Device
supports	O
10	O
times	O
as	O
many	O
LPARs	B-Device
as	O
processors	O
with	O
fractional	O
allocations	O
.	O
</s>
<s>
It	O
was	O
introduced	O
with	O
the	O
POWER5	B-Device
processor	O
.	O
</s>
<s>
All	O
IBM	O
POWER5	B-Device
,	O
POWER6	B-Device
,	O
and	O
successor	O
systems	O
may	O
be	O
partitioned	O
.	O
</s>
<s>
Note	O
that	O
a	O
full	O
system	O
partition	B-Device
may	O
be	O
defined	O
where	O
all	O
resources	O
are	O
consumed	O
by	O
a	O
single	O
partition	B-Device
.	O
</s>
<s>
System	O
P	O
servers	O
with	O
PowerVM	B-Application
enabled	O
allow	O
LPARs	B-Device
with	O
shared	O
CPUs	B-Device
to	O
delegate	O
their	O
unused	O
cycles	O
into	O
the	O
shared	O
pool	O
.	O
</s>
<s>
Unused	O
cycles	O
become	O
available	O
for	O
other	O
partitions	B-Device
and	O
are	O
governed	O
by	O
the	O
parameters	O
specified	O
when	O
the	O
LPAR	B-Device
is	O
defined	O
.	O
</s>
<s>
Changes	O
to	O
a	O
running	O
partition	B-Device
can	O
be	O
made	O
dynamically	O
up	O
to	O
the	O
maximum	O
value	O
set	O
,	O
and	O
down	O
to	O
the	O
minimum	O
value	O
set	O
in	O
the	O
active	O
profile	O
.	O
</s>
<s>
The	O
changing	O
of	O
resource	O
allocations	O
without	O
restart	O
of	O
the	O
logical	B-Device
partition	I-Device
is	O
called	O
dynamic	B-Device
logical	I-Device
partitioning	I-Device
.	O
</s>
<s>
IBM	O
PowerVM	B-Application
is	O
the	O
licensed/purchased	O
feature	O
that	O
enables	O
the	O
virtualization	B-General_Concept
features	O
on	O
p4	O
,	O
5	O
,	O
6	O
,	O
7	O
,	O
and	O
subsequent	O
series	O
servers	O
.	O
</s>
<s>
Exploiting	O
Intel	B-Architecture
vPro	I-Architecture
(	O
i.e.	O
</s>
<s>
Non-uniform	B-Operating_System
memory	I-Operating_System
access	I-Operating_System
)	O
,	O
there	O
are	O
also	O
implementations	O
of	O
Logical	B-Device
Partitioning	I-Device
based	O
on	O
Intel	O
Xeon	O
e.g.	O
</s>
<s>
LPARs	B-Device
(	O
with	O
sufficient	O
certification	O
)	O
safely	O
allow	O
combining	O
multiple	O
test	O
,	O
development	O
,	O
quality	O
assurance	O
,	O
and	O
production	O
work	O
on	O
the	O
same	O
server	O
,	O
offering	O
advantages	O
such	O
as	O
lower	O
costs	O
,	O
faster	O
deployment	O
,	O
and	O
more	O
convenience	O
.	O
</s>
<s>
IBM	O
mainframe	O
LPARs	B-Device
are	O
Common	O
Criteria	O
EAL	O
5+	O
certifiable	O
,	O
equivalent	O
to	O
physically	O
unconnected	O
servers	O
,	O
so	O
they	O
support	O
the	O
highest	O
security	O
requirements	O
,	O
including	O
military	O
use	O
.	O
</s>
<s>
Nearly	O
all	O
IBM	O
mainframes	O
run	O
with	O
multiple	O
LPARs	B-Device
with	O
the	O
IBM	B-Device
System	I-Device
z9	I-Device
and	O
IBM	B-Device
System	I-Device
z10	I-Device
supporting	O
up	O
to	O
60	O
LPARs	B-Device
and	O
later	O
models	O
up	O
to	O
85	O
.	O
</s>
