Hi, We are a bunch of undergraduate students and have put up a cluster of 16 IBM's using LAM for the purpose of running GROMACS. During our simulation test runs we noticed that the running time increases as the number of nodes in the LAM topology increases. We couldn't diagonise the problem...plz help. We used the folowing commands: grompp -v -f full -o full -c after_pr -p speptide -np 16 -shuffle -sort mpirun N -lamd -nger -nsigs mdrun -v -s full -o full -c after_full -g flog We got the following running times with GROMACS 3.1.4... 1 node - 13hrs 5:27 2 nodes - 16hrs 12:59 4 nodes - 17hrs 32:14 8 nodes - 45hrs 00:36 16 nodes - 45hrs 46:55 Thanks in advance Venkat _______________________________________________________________________ Odomos - the only mosquito protection outside 4 walls - Click here to know more! http://r.rediff.com/r?http://clients.rediff.com/odomos/Odomos.htm&&odomos&&wn