Are we alone in the universe? Could life exist on other
planets? Questions like these have inspired countless science
fiction stories, but at theUniversity of Exeter's
Astrophysics department, these queries are at
the forefront of research. The department is using a range of
supercomputers coupled with its own bespoke open source software to
study how stars and planets are formed.
Running computer simulations of how planets and stars form in
different parts of the universe and under many different conditions
should give scientists some indication of what types of planets and
stars they could find in the further reaches of space.
"We want to know where the human race comes from and how many
other solar systems are out there," said
Matthew Bate,
professor of theoretical astrophysics. "Once we understand a little
more about star formation, we can hopefully go forward and make
predictions about how the process might vary in different parts of
the galaxy."
The department has written its own computer program to simulate
how stars are formed. It then uses a powerful computer to run a
detailed simulation of a star formation. However, the department
needs to run simulations of star clusters (several stars) to get an
idea of how accurate the model is. This has increased the computing
power the department requires.
The project uses 1,280 computer cores, which is equivalent to
the processing power of about 300 quad core desktops linked
together. The department is networked using an
infiniband
communications link.
Infiniband allows very quick passing of information packets
between processor nodes, up to 96Gbps. It includes quality of
service and failover, and is a key requirement for the project.
"If you're trying to model a cloud simulation, then each part of
that's cloud formation could be carried out by a different
processor. Because one part of the cloud's formation is dependent
on another part there is a need to pass information between each
different process very quickly, which is why we use this network
fabric," said Bate.
The department has also been forced to install its own
supercomputer to carry on research following the closure of the
computing resources at the UK Astrophysical Fluids Facility.
Funding for the facility ended in 2007 and it was is no longer able
to provide a computational resource to the UK astrophysics
community. A statement on the facility's
website
said it appears unlikely that UKAFF will receive further
funding.
In January, the university took delivery of a 1152-core
SGI Altix ICE 8200, based on Quad-Core Intel Xeon 5400 Series
Processors
"With the new computer in place we can run between 100 to 1,000
simulations at once which gives us very good statistics. It also
allows us to run more precise simulations."
The entire project runs on
SuSE Linux
Enterprise Server (SLES) - a Linux distribution supplied by
Novell. It is targeted for servers, but can be installed on desktop
computers for testing as well. SLES receives much more intense
testing than other SuSE Linux products with the intention that only
mature, stable versions of the included components will make it
through to the released product.
"Astronomers tend to use Unix or Linux-based operating systems
for their work, pretty much exclusively. A lot of our code tends to
be written for those operating systems and we don't write code for
Microsoft Windows," said Bate.
Surprisingly though, the actual code that Bate has written to
perform the analysis on the simulations is written in
Fortran, which
could be run under either Windows or Linux. But because his program
has to interact with other analysis packages that are Linux based,
this has dictated its use as the de facto operating system.
Perhaps the most interesting part of the project is the fact
that it uses no database application even though it generates
terabytes of data. Last year alone the project generated 3-4
terabytes of data. The new supercomputer the department uses has 30
terabytes of disk space.
"You're talking about very large data sets. We tend not to store
them for very long. We'll run the simulation and keep the data for
a year or so on DVDs," said Bate.
The other key aspect of upgrading its IT infrastructure was the
need to keep the computer cool. There wasn't any space left to
install more air conditioning, so it was imperative to build a
cooling module inside the computer. The next thing the university
is looking to install is something called
OpenMP.
OpenMP (Open Multi-Processing) is an
application programming
interface (API) that supports multi-platform shared memory
multiprocessing programming in C/C++ and Fortran on many
architectures, including Unix and Microsoft Windows platforms. An
application built with the hybrid model of parallel programming can
run on a computer cluster using both OpenMP and
Message
Passing Interface (MPI).
A key milestone ahead for the project this year will be when it
runs a simulation of the collapse of gas containing 500,000 times
the mass of the sun. As the temperatures in space increase, it
looks as though computing power is keeping pace, too.