Administrator Guide

Performance characterization
33 Dell EMC Ready Solution for HPC PixStor Storage | Document ID
mpirun --allow-run-as-root -np $Threads --hostfile my_hosts.$Threads --prefix
/mmfs1/perftest/ompi --mca btl_openib_allow_ib 1
/mmfs1/perftest/lanl_ior/bin/mdtest -v -d /mmfs1/perftest/ -i 1 -b $Directories
-z 1 -L -I 1024 -y -u -t -F
Since performance results can be affected by the total number of IOPs, the number of files per directory and
the number of threads, it was decided to keep fixed the total number of files to 2 MiB files (2^21 = 2097152),
the number of files per directory fixed at 1024, and the number of directories varied as the number of threads
changed as shown in Table 4 in the first benchmark characterization section.
Figure 18 Metadata Performance - Empty Files
First, notice that the scale chosen was logarithmic with base 10, to allow comparing operations that have
differences several orders of magnitude; otherwise some of the operations would look like a flat line close to 0
on a normal graph. A log graph with base 2 could be more appropriate, since the number of threads are
increased in powers of 2, but the graph would look very similar and people tend to handle and remember
better numbers based on powers of 10.
The system gets very good results with Stat and Read operations reaching their peak value at 64 threads with
almost 11M op/s and 4.7M op/s respectively. Removal operations attained the maximum of 170.6K op/s at 16
threads and Create operations achieving their peak at 32 threads with 222.1K op/s. Stat and Read operations
have more variability, but once they reach their peak value, performance does not drop below 3M op/s for
Stats and 2M op/s for Reads. Create and Removal are more stable once their reach a plateau and remain
above 140K op/s for Removal and 120K op/s for Create. Notice the extra drives do not affect much most of
the metadata operations on empty files as expected.