mdtest is a synthetic MPI parallel benchmark for testing the metadata performance of filesystems. Each thread operates on its own working set.

The benchmark operates in phases (excerpt):

• Creation of directories
• Creation of files
• Reading files
• Deletion of files
• Deletion of the tree

Here are a few important command line arguments:

• -d Target directory to run the test on
• -i Iterations, the benchmark is repeated this number of times to investigate standard deviation
• -z Depth of the hierarchical directory structure
• -b Branching factor, how many directories to create, used in conjunction with -z
• -I Number of files to create per directory
• -w Write this number of bytes to each file after it is created
• -r Read this number of bytes from each file in the read phase

To print the internal operations of the benchmark add -v -v -v to the tool.

For example runnning mpiexec -n 2 ./mdtest -d /tmp/ -b 10 -i 1 -I 100 (using mdtest version 1.9.3) results in the following output

-- started at 12/02/2016 11:15:22 --

mdtest-1.9.3 was launched with 2 total task(s) on 1 node(s)
Command line used: ./mdtest -d /tmp/ -b 10 -i 1 -I 100
Path: /tmp
FS: 15.6 GiB   Used FS: 0.0%   Inodes: 3.9 Mi   Used Inodes: 0.0%

2 tasks, 200 files/directories

SUMMARY: (of 1 iterations)
   Operation                      Max            Min           Mean        Std Dev
   ---------                      ---            ---           ----        -------
   Directory creation:     452704.155     452704.155     452704.155          0.000
   Directory stat    :     900065.236     900065.236     900065.236          0.000
   Directory removal :     502612.822     502612.822     502612.822          0.000
   File creation     :     353353.328     353353.328     353353.328          0.000
   File stat         :    1184831.638    1184831.638    1184831.638          0.000
   File read         :     783982.056     783982.056     783982.056          0.000
   File removal      :     716362.767     716362.767     716362.767          0.000
   Tree creation     :     199728.762     199728.762     199728.762          0.000
   Tree removal      :     246723.765     246723.765     246723.765          0.000

-- finished at 12/02/2016 11:15:22 --