Computational Cluster Programs

Computing on the Hoffman2 Cluster

The preferred way to access the Hoffman2 Cluster is through the UCLA Grid Portal at http://grid.ucla.edu. The grid portal makes the Hoffman2 Cluster accessible from any web browser. You can submit batch jobs, run interactive GUI applications and get an xterm from the UCLA Grid Portal. If you are going to access the Hoffman2 Cluster from the UCLA Grid Portal and use batch or interactive services (except for xterm), you will not need to know the information presented here.

Role of the Head Nodes

Use the Hoffman2 head nodes for logging into the Hoffman2 Cluster.

You may do the following when logged onto a Hoffman2 Cluster head node:

  • File management
  • Editing
  • Compile programs from source code
  • Start up ATS-supplied interactive application such as: Matlab, Maple, etc.

Do not Compute on the Head Nodes

Do not run any your own applications, or any applications other than ATS-supplied applications on a Hoffman2 Cluster head node. The load average on the head nodes is continously monitored and any user processes that is contributing significantly to the load average is terminated without notice.

Running Interactive Programs

There are 2 interactive nodes that are provided for software development, debugging, and running interactive applications for 1 hour or less. Their names are i01 and i02. They can be accessed from the head node using the commands:

ssh i01

and,

ssh i02

If your interactive application has a GUI interface which requires that the DISPLAY environment variable is set correctly, use the ssh -X option to access these nodes. Example:

ssh -X i01

Note that i01 and i02 are shared by many users, therefore do not run multi-threaded programs, or programs that require more than the default amount of memory, or programs that require more than 1 hour of run time on these nodes.

If you need to run your program interactively for longer than 1 hour, or if your program is multi-threaded and needs to run on more than one core, or with more than the default amount of memory, you can request an interactive session from the Sun Grid Engine from the pool of compute nodes. Please see:

How to Get an Interactive Session through SGE

You do not need to do this for commercial programs, like Matlab, which already have suitable options built into their startup scripts.

Batch Jobs

Most of the nodes on the Hoffman2 Cluster are dedicated to running batch jobs. All non-interactive programs that require more than 1 hour to complete must be submitted as batch jobs to the Sun Grid Engine (SGE).