A Commodity Cluster for Lattice QCD Calculations at DESY
========================================================
A. Gellrich, H. Wittig
DESY Hamburg

P. Wegner
DESY Zeuthen

At the beginning of 2002 DESY Hamburg set up a new commodity cluster for
QCD lattice calculations. It consists of 32 rack-mounted dual-CPU PCs
interconnected by a Myrinet2000 network plus one master server. The
operating system is a SuSE-based Linux distribution, including MPI-GM for
message passing. 16 PCs are equipped with 2.0 GHz Intel Xeon processors,
16 PCs run 1.7 GHz Xeon CPUs. All PCs have 512 MB of memory.
The cluster nodes are operated in a separate subnet of the master server
based on Fast-Ethernet with GigaBit-Ethernet up-links.
Status information of all nodes can be retrieved by way of a home-made
monitoring tool over the web.
The cluster is connected via the master server to DESY's mass storage
system to allow for archiving of checkpoints and results. In order to
optimize the access to the storage media, the recently at DESY introduced
dCache mechanism is used. The anticipated data volume is a few Terabyte
per year.

In the presentation at CHEP2003 we will introduce the cluster and its
set-up. We will discuss experiences gained during one year of operation
and present benchmark results.