Notes on the usage of the HPC cluster

The cluster is composed of 6 nodes.
The front-end to which you can access via ssh is: hpc.dsi.unive.it
For example:

%> ssh -X studXX@hpc.dsi.unive.it

This front-end machine has two network interfaces. One of these interfaces is connected to a fast Gigabit switch with all the other 5 hosts. The /etc/hosts file contains the domain names of all these hosts:

192.168.100.1   master 
192.168.100.101 node001 
192.168.100.102 node002 
192.168.100.103 node003 
192.168.100.104 node004 
192.168.100.105 node005

Note that hpc and master are two domain names for the same physical host.

The home directories are located on the disks of the host master, which exports them to all the other nodes of the cluster.

To run an MPI program written in C, compile using the scripts mpicc, install the public key on .ssh/authorized_keys in the home directory, prepare a file (e.g. hosts) with the names of the 6 machines (master, node001, node002, node003, node004, node005), and run programs using mpirun. For example:

%> mpirun -np 2 -machinefile hosts ./cpi

On each machine you can use the local disk to store input/output/temporary files accessed/produced by the various MPI tasks.
This local disk on each node corresponds to the /scratch directory.