Hi I am trying to use an MPI program to manage an ensemble of apruns under Cobalt on Theta. I compiled an MPICH 3.2 for the login node. Then, in an interactive allocation, I do: $ hostname thetamom2 $ mpiexec -launcher fork -n 1 echo hi [mpiexec@thetamom2] HYDU_parse_hostfile (utils/args/args.c:319): unable to open host file: /var/tmp/cobalt.222331 [mpiexec@thetamom2] HYDT_bscd_cobalt_query_node_list (tools/bootstrap/external/cobalt_query_node_list.c:27): error parsing hostfile [mpiexec@thetamom2] HYDT_bsci_query_node_list (tools/bootstrap/src/bsci_query_node_list.c:19): RMK returned error while querying node list [mpiexec@thetamom2] main (ui/mpich/mpiexec.c:186): unable to query the RMK for a node list It looks like Hydra has detected that it is under Cobalt. How do I force it to ignore Cobalt? Ultimately, I plan to replace 'echo' with a shell script that does an aprun. Thanks -- Justin M Wozniak _______________________________________________ discuss mailing list [email protected] To manage subscription options or unsubscribe: https://lists.mpich.org/mailman/listinfo/discuss