The HERMES Data Production PC Farm
Paper: 199
Session: G (talk)
Speaker: Wander, Wolfgang, Universitaet Erlangen-Nuernberg
Keywords: commodity computing, off-the-shelf products, PC operating systems, free software
The HERMES Data Production PC Farm
Wolfgang Wander
Univ. Erlangen-Nuernberg / Erwin-Rommel-Str. 1 / D-91058 Erlangen
HERMES-Collaboration/DESY
Abstract
Commodity computing hardware nowadays offers large gains in the
price/performance ratio and therefore becomes more and more attractive
to HEP experiments. A large increase in the computing power
requirements at the HERMES experiment at DESY forced us to double our
available offline CPU resources. Data production so far had been done
on a 28-Processor SGI Challenge. Investigation of the
price/performance ratio of various upgrade solutions resulted in the
decision to build up a PC farm of 10 PPro systems in Sep 96. The
choice of the operating system was based on the requirements for data
and Monte-Carlo production and led to the Unix flavour Linux. Here we
showed that unlike on other PC operating systems (like Windows NT) the
overhead of porting the available software base to a new operating
system is small to neglectible. Two men-weeks of porting the 600000
lines of hermes software resulted in a first production run of the
farm already one week after the delivery. The performance of the PPro
processor together with the better system performance of the Linux
operating system decreases the reconstruction time per CPU by more
than a factor of 2 over a single CPU in the SGI Challenge. A
Fast-Ethernet network connection provides the required bandwidth to
the DESY backbone for raw data access. Currently the PC farm is used
for various Monte-Carlo calculations and will go into full production
mode after the end of 96 data taking in December 1996.