Dell PowerEdge SDS 100 Improving NFS performance on HPC clusters with Dell Flu - Page 37

Improving NFS Performance on HPC Clusters with Dell Fluid Cache for DAS B.2. mdtest mdtest can be downloaded from http://sourceforge.net/projects/mdtest/. Version 1.8.3 was used in these tests. It was compiled and installed on a NFS share that was accessible by compute nodes. mdtest is launched with mpirun. For these tests, Intel MPI version 4.1.0 was used. One million files were created, stated and unlinked concurrently from multiple NFS clients on the NFS server. The following table describes the mdtest command-line arguments. mpirun ARGUMENT DESCRIPTION -np Number of processes -hostfile Tells mpirun where the hostfile is -d The directory mdtest should run in -i The number of iterations the test will run -b Branching factor of directory structure -z Depth of the directory structure -L Files only at leaf level of tree -I Number of files per directory tree -y Sync the file after writing -u unique working directory for each task -C Create files and directories -R Randomly stat files -T Only stat files and directories -r Remove files and directories left over from run As with the IOzone random access patterns, the following procedure was followed to minimize cache effects during the metadata testing: • Unmount NFS share on clients. • Stop the NFS service and umount the XFS file system on the server. • Mount XFS file system on the server and start the NFS service. • Mount NFS Share on clients. 37