One more thing: I ssh'd to the node where mpiblast is running, and there is an ssh attempt to the other nodes from the machines file: (ps -elf output) 0 S idoerg 5795 5645 0 75 0 - 4660 - 15:16 ? 00:00:00 ssh ikelite-3-1 -l idoerg -n /opt/Bio/mpiblast/bin/mpiblast ikelite-3-0 35878 \-p4amslave \-p4yourname ikelite-3-1 \-p4rmrank 3 0 S idoerg 5796 5645 0 76 0 - 4660 - 15:16 ? 00:00:00 ssh ikelite-3-1 -l idoerg -n /opt/Bio/mpiblast/bin/mpiblast ikelite-3-0 35878 \-p4amslave \-p4yourname ikelite-3-1 \-p4rmrank 4 0 S idoerg 5797 5645 0 76 0 - 4660 - 15:16 ? 00:00:00 ssh ikelite-3-1 -l idoerg -n /opt/Bio/mpiblast/bin/mpiblast ikelite-3-0 35878 \-p4amslave \-p4yourname ikelite-3-1 \-p4rmrank 5 0 S idoerg 5798 5645 0 75 0 - 4660 - 15:16 ? 00:00:00 ssh ikelite-1-2 -l idoerg -n /opt/Bio/mpiblast/bin/mpiblast ikelite-3-0 35878 \-p4amslave \-p4yourname ikelite-1-2 \-p4rmrank 6 0 S idoerg 5799 5645 0 76 0 - 4660 - 15:16 ? 00:00:00 ssh ikelite-1-4 -l idoerg -n /opt/Bio/mpiblast/bin/mpiblast ikelite-3-0 35878 \-p4amslave \-p4yourname ikelite-1-4 \-p4rmrank 7 0 S idoerg 5800 5645 0 75 0 - 4660 - 15:16 ? 00:00:00 ssh ikelite-3-7 -l idoerg -n /opt/Bio/mpiblast/bin/mpiblast ikelite-3-0 35878 \-p4amslave \-p4yourname ikelite-3-7 \-p4rmrank 8 0 S idoerg 5801 5645 0 76 0 - 4660 - 15:16 ? 00:00:00 ssh ikelite-3-7 -l idoerg -n /opt/Bio/mpiblast/bin/mpiblast ikelite-3-0 35878 \-p4amslave \-p4yourname ikelite-3-7 \-p4rmrank 9 0 S idoerg 5802 5645 0 76 0 - 4660 - 15:16 ? 00:00:00 ssh ikelite-3-7 -l idoerg -n /opt/Bio/mpiblast/bin/mpiblast ikelite-3-0 35878 \-p4amslave \-p4yourname ikelite-3-7 \-p4rmrank 10 0 S idoerg 5803 5645 0 76 0 - 4660 - 15:16 ? 00:00:00 ssh ikelite-0-12 -l idoerg -n /opt/Bio/mpiblast/bin/mpiblast ikelite-3-0 35878 \-p4amslave \-p4yourname ikelite-0-12 \-p4rmrank 11 -- I. Friedberg "The only problem with troubleshooting is that sometimes trouble shoots back."