I have: -Ubuntu 12.4 -rsh-redo-rsh -three machines -mpich3 -have tried export HYDRA_DEMUX=select / poll -have tried ssh/rsh -have added to LIBS: event_core event_pthreads I can run test at on to two machines whitout error but when I take third machine to cluster demux engine goes mad,... there is connection hanging,... and nothing happens,... <MPITEST> <NAME>uoplong</NAME> <NP>11</NP> <WORKDIR>./coll</WORKDIR> <STATUS>fail</STATUS> <TESTDIFF> [mpiexec@mpi1] APPLICATION TIMED OUT [proxy:0:0@mpi1] HYD_pmcd_pmip_control_cmd_cb (./pm/pmiserv/pmip_cb.c:886): assert (!closed) failed [proxy:0:0@mpi1] HYDT_dmxu_poll_wait_for_event (./tools/demux/demux_poll.c:77): callback returned error status [proxy:0:0@mpi1] main (./pm/pmiserv/pmip.c:206): demux engine error waiting for event [mpiexec@mpi1] HYDT_bscu_wait_for_completion (./tools/bootstrap/utils/bscu_wait.c:76): one of the processes terminated badly; aborting [mpiexec@mpi1] HYDT_bsci_wait_for_completion (./tools/bootstrap/src/bsci_wait.c:23): launcher returned error waiting for completion [mpiexec@mpi1] HYD_pmci_wait_for_completion (./pm/pmiserv/pmiserv_pmci.c:188): launcher returned error waiting for completion [mpiexec@mpi1] main (./ui/mpich/mpiexec.c:331): process manager error waiting for completion </TESTDIFF> </MPITEST> Also I can run joni@mpi1:/mpi3/S3/hpcc-1.4.2$ mpiexec -np 6 hostname mpi1 mpi1 ugh ugh kaak kaak but if I run joni@mpi1:/mpi3/S3/hpcc-1.4.2$ mpiexec -np 6 ls I get only one directory as output and system will cease until I have re-started slave machines ! -- Joni-Pekka Kurronen AMRINA, Insin��ri AMK veneala