howtos frontend run jobs

Sometimes you have a situation where you want your frontend to act like a compute node and run jobs submitted to your queuing system. This might be because you only have one 48-core machine, or you have a modest cluster and want to utilize the cores on your frontend.

1. Add your frontend to SGE

See sun-gridengine#Add_Frontend_as_a_SGE_Execution_Host_in_Rocks

2. Add your frontend to Torque/Maui (PBS)

If you have installed the Torque roll, issue the following commands as root on the frontend. These commands assume you use tcsh/csh, but bash should be similar.

The first line setting $frontend just assures that the name matches that returned by /bin/hostname (which is generally the FQDN). They must match, or pbs_mom will refuse to start/work.

The next two lines set the number of cores to be used for running jobs. You probably should reserve a few cores for all the Rocks overhead processes, and for interactive logins, compiling, etc. In this example, we save 4 cores for the overhead and assign the rest for jobs. This is accomplished by setting the "np = $N" (np means number of processors) value.

# set frontend = `/bin/hostname`
# set N = `cat /proc/cpuinfo | grep processor | wc -l`
# set N = `expr $N - 4`    # reserve 4 cores
# 
# qmgr -c "create node $frontend"
# qmgr -c "set node $frontend np = $N"
# qmgr -c "set node $frontend ntype=cluster"
# service pbs_server restart

Alternatively, you can edit /opt/torque/server_priv/nodes by hand, and do the "service pbs_server restart" to make it re-read the file.

Next, make sure pbs_mom is started on the frontend:

# scp compute-0-0:/etc/pbs.conf /etc
# chkconfig --add pbs
# service pbs start

If you have no compute nodes, you can create /etc/pbs.conf by hand. It should look like this:

pbs_home=/opt/torque
pbs_exec=/opt/torque
start_mom=1
start_sched=0
start_server=0

You should now be able to see the frontend listed in the output of "pbsnodes -a", and any jobs submitted to the queue will run there.

--Bart 13:11, 6 October 2010 (EDT)

category:HOWTOs