Example Build of an ARC/Condor Cluster
Introduction
A multi-core job is one which needs to use more than one processor on a node. Until recently, multi-core jobs have not been used on the grid infrastructure. This has all changed because Atlas and other large users have now asked sites to enable multi-core on their clusters.
Unfortunately, it is not just a simple task of setting some parameter on the head node and sitting back while jobs arrive. Different grid system have varying levels of support for multi-core, ranging from non-existent to virtually full support.
This report discusses the multi-core configuration at Liverpool. We decided to build a test cluster using one of the most capable batch systems currently available, called HTCondor (or condor for short). We also decided to fron the system with an ARC/Condor CE.
Infrastructure/Fabric
The multicore test cluster consists of an SL6 headnode to run the ARC CE and the Condor batch system. The headnode has a dedicated set of 11 workernodes of various types, providing a total of 96 single threads of execution.
Head Node
The headnode is a virtual system running on KVM.
| Host Name | OS | CPUs | RAM | Disk Space
|
|---|---|---|---|---|
| hepgrid2.ph.liv.ac.uk | SL6.4 | 8 | 2 gig | 35 gig |
Worker nodes
The physical workernodes are described below.
| Rack names | CPU type | CPUs Per Node | Slots used per cpu | Slots used per node | Total nodes | Total slots | HepSpec per slot | Total hepspec | OS | RAM | Disk Space
|
|---|---|---|---|---|---|---|---|---|---|---|---|
| r21-n01-4 | E5620 | 2 | 5 | 10 | 4 | 8 | 12.05 | 482 | SL6.4 | 24 GB | 1.5 TB |
