[[!meta  title="Notes on using and managing clusters"]]

Using
-----

Our cluster runs the open source [Torque][]/[Maui][] [[portable batch
scheduling system|PBS]] (PBS).  A batch scheduler takes user submitted
jobs, and distributes them across the the cluster in an intelligent
manner, so users don't need to worry about sharing resources fairly or
[[ssh]]ing into compute nodes to start their jobs.  Users submit jobs
to the queue using `qsub`.  I've compiled my own [[brief
intro|pbs_queues]] to `qsub`, and there are lots more floating about
the internet.

While PBS queues are great for distributing embarassingly parallel
jobs across the cluster, your application may need processes running
on seperate compute nodes to share data.  A common approach is to use
the [[Message Passing Interface|MPI]] (MPI).  Our cluster uses the
[mpich2][] implementation.  Cluster-aware applications written in MPI
can be started through Torque using an [alternate mpiexec][mpiexec]
from the [Ohio Supercomputer Center][OSC].  There is a nice, brief
[introduction][] by Kristina Wanous at the [University of Northern
Iowa][UNI].

Managing
--------

Our cluster (9 dual-core nodes) runs [Debian][].  The compute nodes
all boot to [[NFS roots|nfs_root]] off the server node.  Once that
hurdle was passed, setting up Torque, Maui, mpich2, and mpiexec was
pretty simple, mostly the usual:

    wget ...
    tar ...
    configure ...
    make
    make install

with a bit of configuring for our setup.  I'll put up some more
detailed notes and our config options when I get the time.

[[!tag tags/linux]]
[[!tag tags/hardware]]

[Torque]: http://www.clusterresources.com/pages/products/torque-resource-manager.php
[Maui]: http://www.clusterresources.com/pages/products/maui-cluster-scheduler.php
[mpich2]: http://www.mcs.anl.gov/research/projects/mpich2/
[mpiexec]: http://www.osc.edu/~djohnson/mpiexec/
[OSC]: http://www.osc.edu/~djohnson/mpiexec/
[introduction]: http://debianclusters.cs.uni.edu/index.php/MPICH_with_Torque_Functionality
[UNI]: http://www.uni.edu/
[Debian]: http://www.debian.org/