ParaStation MPI is also able to start up serial tasks, which are not counted within the process management. Those tasks are called administrative tasks. Thus, an arbitrarily number of tasks can be placed on a particular node, even if there are already parallel tasks spawned.

In order to start an administrative task on a node, execute

  # pssh -h nodename program args

This will run the command program on the node nodename providing it the arguments [args].

By default, only root is allowed to run this type of tasks, as this may burden unexpected load onto a compute node. To enable other users, there id must be added to the adminuser list or the user's group must be added to the admingroup list. For details, refer to psiadmin(8) and parastation.conf(5).

In addition to pssh, the mpiexec command may be used to run one or more administrative tasks in parallel. Use the option --admin to do so:

  # mpiexec -np 1 --admin --hosts nodename program args

The nodename may be a particular hostname or a (command separated) list of hosts.