Home > Workload Solutions > High Performance Computing > White Papers > HPC Software-Defined Storage with PixStor > Metadata Performance with MDtest Using 4 KiB Files
This test is almost exactly identical to the previous one, except that instead of empty files, small files of 4KiB were used. The following command was used to execute the benchmark, where Threads was the variable with the number of threads used (1 to 512 incremented in powers of two), and my_hosts.$Threads is the corresponding file that allocated each thread on a different node, using round robin to spread them homogeneously across the 16 compute nodes.
mpirun --allow-run-as-root -np $Threads --hostfile my_hosts.$Threads –map-by node --mca btl_openib_allow_ib 1 --oversubscribe --prefix /usr/mpi/gcc/openmpi-4.1.2a1 /usr/local/bin/mdtest -v -d /mmfs1/perf/mdtest -P -i 1 -b $Directories -z 1 -L -I 1024 -u -t -F -w 4K -e 4K
The system gets very good results for Stat and Removal operations reaching their peak value at 256 threads with 8.62M op/s and 5.65M op/s respectively. Removal operations attained the maximum of 285.86K Op/s and Create operations achieving their peak with 70.76K op/s, both at 256 threads. Stat and Reads operations have more variability, but once they reach their peak value, performance does not drop below 4M op/s for Stats and 3.2M op/s for Reads. Create and Removal have less variability, creates keep increasing as the number of threads grows, and removals slowly decrease after reaching its peak value.
Since these numbers are for a metadata module with a single PowerVault ME4024, performance will increase for each additional PowerVault ME4024 arrays, however we cannot assume a linear increase for each operation. Unless the whole file fits inside the inode for such file, data targets on the PowerVault ME4084s will be used to store small files, limiting the performance to some degree.