How to use a "Rocks" cluster

Question

Hi,

I've just joined a research lab at my University and been given access to a Cluster to compile and run the c++ code that I write. I use SSH to access it and simply use the cluster like a Linux terminal.

I often have to wait a relatively long time while my code runs. I'm trying to figure out if there's a more efficient way use the Cluster. For example, there are different CPUs/Nodes in the cluster, some of which are more in use and others less in use. How do I access a specific CPU? I have access to the "Ganglia" overview page which gives information about the different Nodes.

Also, if I run 2 processes in a different SSH windows will it automatically use different processors or nodes, or do I have to manually specify that.

I couldn't find any documentation to help me with these issues, so I'd appreciate a little help.

Thanks

Answer 1

Simply running something on a cluster does not mean it is taking advantage of the cluster at all. By default, it will probably just run on the head node. Software needs to be written specifically for a cluster.

There is likely to be some kind of scheduler running that you need to interface with. Perhaps you could also see if distcc is installed and configured for your particular cluster (for doing the compilation across multiple machines). There may also be a particular flavour of MPI running to allow processes on different nodes to communicate.

Clusters software setups tend to be very specialised to the hardware and computing environment. Really, I would recommend that you ask someone who has used the machine before these kinds of questions, because any advice you receive here is unlikely to be completely accurate for your particular cluster.