Dear all, We have a diskless cluster with these specs: 1) A server which has some disks. Root directories (/usr, /lib, ...) are
on /dev/sda while /home is on /dev/sdb and these are two physical hard drives. 2) Some compute nodes. These don't have any disk drive instead they are connected through a 10/100/1000 switch to the server 3) Nodes uses a NFS directory for booting which resides on /dev/sda. In our cluster we use openmpi with openfoam. Both were compiled using default options. Problem is when the openfoam solver with openmpi is sent to a compute node, the opnempi uses a lot of *WRITE* operations which causes a low cpu utilization and hence the processes are mainly in 'D' state. A brief description of our tests are: We ssh to the compute node and run the application there Test 1) One process of openfoam is launched without openmpi. Everything is fine and cpu is utilized 100% Test 2) Two processes of openfoam is launched (mpirun -np 2 ....). Two openfoam processes has about 30% cpu utilization and they are in 'D' state most of the time. Is there any suggestion on that. That is a really poor performance Regards, Mahmood
