Hardware Reference
In-Depth Information
Item
BlueGene/P
Red Storm
CPU
32-Bit PowerPC
64-Bit Opteron
Clock
850 MHz
2.4 GHz
Compute CPUs
294,912
20,736
CPUs/board
128
8
CPUs/cabinet
4096
192
Compute cabinets
72
108
Teraflops/sec
1000
124
Memory/CPU
512 MB
2-4 GB
Total memory
144 TB
10 TB
Router
PowerPC
Seastar
Number of routers
73,728
10,368
Interconnect
3D torus 72
×
32
×
32
3D torus 27
×
16
×
24
Other networks
Gigabit Ethernet
Fast Ethernet
Partitionable
No
Yes
Compute OS
Custom
Custom
I/O OS
Linux
Linux
Vendor
IBM
Cray Research
Expensive
Yes
Yes
Figure 8-42.
A comparison of BlueGene/P and Red Storm.
The two machines were built in the same time frame, so their differences are
due not to technology but to designers' different visions and to some extent to the
differences between the builders, IBM and Cray. BlueGene/P was designed from
the beginning as a commercial machine, which IBM hopes to sell in large numbers
to biotech, pharmaceutical, and other companies. Red Storm was built on special
contract with Sandia, although Cray plans to make a smaller version for sale, too.
IBM's vision is clear: combine existing cores to produce a custom chip that
can be mass produced cheaply, run it at a low speed, and hook together a very large
number of them using a modest-speed communication network. Sandia's vision is
equally clear, but different: use a powerful off-the-shelf 64-bit CPU, design a very
fast custom router chip, and throw in a lot of memory to produce a far more pow-
erful node than BlueGene/P so fewer will be needed and communication between
them will be faster.
These decisions had consequences for the packaging. Because IBM built a
custom chip combining the processor and router, it achieved a higher packing den-
sity: 4096 CPUs/cabinet. Because Sandia went for an unmodified off-the-shelf
CPU chip and 2-4 GB of RAM per node, it could get only 192 compute processors
in a cabinet. Consequently, Red Storm takes up more floor space and consumes
more power than BlueGene/P.
