<s>
iDataCool	B-Device
is	O
a	O
high-performance	B-Architecture
computer	I-Architecture
cluster	O
based	O
on	O
a	O
modified	O
IBM	B-Operating_System
System	I-Operating_System
x	I-Operating_System
iDataPlex	B-Device
.	O
</s>
<s>
The	O
cluster	O
serves	O
as	O
a	O
research	O
platform	O
for	O
cooling	O
of	O
IT	B-General_Concept
equipment	O
with	O
hot	O
water	O
and	O
efficient	O
reuse	O
of	O
the	O
waste	O
heat	O
.	O
</s>
<s>
It	B-General_Concept
is	O
funded	O
by	O
the	O
German	O
Research	O
Foundation	O
(	O
DFG	O
)	O
,	O
the	O
German	O
state	O
of	O
Bavaria	O
,	O
and	O
IBM	O
.	O
</s>
<s>
The	O
iDataCool	B-Device
high-performance	O
compute	O
cluster	O
is	O
a	O
research	O
project	O
on	O
cooling	O
with	O
hot	O
water	O
and	O
energy	O
reuse	O
in	O
data	B-Operating_System
centers	I-Operating_System
.	O
</s>
<s>
The	O
waste	O
heat	O
of	O
iDataCool	B-Device
is	O
used	O
to	O
drive	O
an	O
adsorption	O
chiller	O
that	O
generates	O
chilled	O
water	O
.	O
</s>
<s>
The	O
iDataCool	B-Device
cluster	O
has	O
been	O
operating	O
with	O
hot-water	O
cooling	O
since	O
2011	O
.	O
</s>
<s>
Members	O
of	O
the	O
project	O
have	O
also	O
been	O
active	O
in	O
other	O
supercomputer	B-Architecture
projects	O
such	O
as	O
QCDOC	B-Operating_System
and	O
QPACE	B-General_Concept
.	O
</s>
<s>
SuperMUC	B-Device
is	O
based	O
on	O
the	O
cooling	O
technology	O
invented	O
for	O
QPACE	B-General_Concept
,	O
Aquasar	O
,	O
and	O
iDataCool	B-Device
.	O
</s>
<s>
The	O
iDataCool	B-Device
research	O
project	O
was	O
presented	O
at	O
the	O
International	O
Supercomputing	B-Architecture
Conference	O
in	O
Leipzig	O
,	O
Germany	O
,	O
in	O
2013	O
,	O
which	O
led	O
to	O
it	B-General_Concept
being	O
featured	O
in	O
several	O
articles	O
.	O
</s>
<s>
Power	O
and	O
cooling	O
of	O
IT	B-General_Concept
equipment	O
are	O
of	O
major	O
concern	O
for	O
modern	O
data	B-Operating_System
centers	I-Operating_System
.	O
</s>
<s>
Since	O
1996	O
the	O
worldwide	O
costs	O
for	O
power	O
and	O
cooling	O
of	O
IT	B-Application
infrastructure	I-Application
have	O
increased	O
by	O
more	O
than	O
a	O
factor	O
of	O
five	O
.	O
</s>
<s>
Conventionally	O
,	O
data	B-Operating_System
centers	I-Operating_System
use	O
air	O
as	O
the	O
primary	O
cooling	O
medium	O
for	O
the	O
IT	B-General_Concept
equipment	O
.	O
</s>
<s>
While	O
air	O
cooling	O
is	O
simple	O
and	O
flexible	O
it	B-General_Concept
also	O
has	O
some	O
disadvantages	O
,	O
e.g.	O
,	O
limited	O
packaging	O
density	O
and	O
limited	O
options	O
for	O
energy	O
reuse	O
.	O
</s>
<s>
Liquid	O
cooling	O
has	O
recently	O
resurfaced	O
in	O
the	O
sector	O
of	O
high-performance	B-Architecture
computing	I-Architecture
.	O
</s>
<s>
Since	O
2009	O
the	O
Green500	O
list	O
of	O
the	O
most	O
energy-efficient	O
supercomputers	B-Architecture
is	O
dominated	O
by	O
liquid-cooled	O
designs	O
.	O
</s>
<s>
Leibniz-Rechenzentrum	B-General_Concept
in	O
Germany	O
,	O
where	O
SuperMUC	B-Device
drives	O
the	O
heating	O
of	O
the	O
data	B-Operating_System
center	I-Operating_System
during	O
winter	O
with	O
roughly	O
1	O
MW	O
recovered	O
from	O
the	O
compute	O
equipment	O
.	O
</s>
<s>
The	O
latter	O
option	O
,	O
which	O
is	O
the	O
design	O
target	O
of	O
iDataCool	B-Device
,	O
requires	O
a	O
high	O
quality	O
of	O
the	O
heat	O
,	O
which	O
can	O
only	O
be	O
achieved	O
by	O
direct	O
hot-water	O
cooling	O
.	O
</s>
<s>
The	O
aim	O
of	O
iDataCool	B-Device
was	O
to	O
achieve	O
coolant	O
temperatures	O
of	O
more	O
than	O
65°C	O
,	O
at	O
which	O
commercially	O
available	O
adsorption	O
chillers	O
tend	O
to	O
become	O
efficient	O
,	O
and	O
to	O
demonstrate	O
the	O
long-term	O
stability	O
of	O
a	O
large	O
production	O
machine	O
under	O
these	O
conditions	O
.	O
</s>
<s>
The	O
iDataCool	B-Device
installation	O
at	O
the	O
University	O
of	O
Regensburg	O
consists	O
of	O
three	O
IBM	B-Operating_System
System	I-Operating_System
x	I-Operating_System
iDataPlex	B-Device
racks	O
.	O
</s>
<s>
Each	O
rack	B-Application
contains	O
72	O
compute	O
nodes	O
.	O
</s>
<s>
A	O
compute	O
node	O
consists	O
of	O
two	O
Intel	B-Device
Xeon	I-Device
Westmere	I-Device
server	O
processors	O
and	O
is	O
arranged	O
as	O
a	O
distributed	B-Operating_System
shared	I-Operating_System
memory	I-Operating_System
system	O
with	O
24	O
GB	O
of	O
DDR3-SDRAM	O
.	O
</s>
<s>
Switched	O
Infiniband	B-Architecture
is	O
used	O
for	O
communication	O
amongst	O
the	O
nodes	O
.	O
</s>
<s>
The	O
original	O
iDataPlex	B-Device
system	O
is	O
entirely	O
cooled	O
by	O
air	O
.	O
</s>
<s>
The	O
ambient	O
air	O
in	O
the	O
data	B-Operating_System
center	I-Operating_System
is	O
drawn	O
in	O
through	O
perforated	O
front	O
doors	O
,	O
and	O
the	O
hot	O
air	O
is	O
blown	O
back	O
into	O
the	O
data	B-Operating_System
center	I-Operating_System
on	O
the	O
back	O
side	O
.	O
</s>
<s>
Components	O
that	O
need	O
cooling	O
are	O
the	O
power	O
supplies	O
,	O
network	B-Protocol
switches	I-Protocol
,	O
and	O
compute	O
nodes	O
.	O
</s>
<s>
All	O
conversions	O
of	O
the	O
original	O
iDataPlex	B-Device
cluster	O
were	O
performed	O
at	O
the	O
University	O
of	O
Regensburg	O
.	O
</s>
<s>
The	O
data	B-Operating_System
center	I-Operating_System
of	O
the	O
university	O
was	O
extended	O
to	O
provide	O
the	O
liquid-cooling	O
infrastructure	O
.	O
</s>
<s>
iDataCool	B-Device
allows	O
for	O
cooling	O
with	O
hot	O
water	O
at	O
temperatures	O
of	O
up	O
to	O
70°C	O
.	O
</s>
<s>
The	O
waste	O
heat	O
of	O
iDataCool	B-Device
drives	O
a	O
low-temperature	O
adsorption	O
chiller	O
(	O
LTC	O
09	O
by	O
InvenSor	O
)	O
that	O
works	O
efficiently	O
already	O
at	O
temperatures	O
around	O
65°C	O
.	O
</s>
<s>
The	O
chiller	O
generates	O
chilled	O
water	O
that	O
is	O
used	O
to	O
cool	O
other	O
compute	O
equipment	O
in	O
the	O
data	B-Operating_System
center	I-Operating_System
.	O
</s>
