Python script for checking disk IOPS and write latency

Different Maximo components require different minimal disk performance abilities in order to see optimal performance. The python script found here can be used to test important disk (ie, physical volume) characteristics on pods that contain python.

Directions for using the disk-iops-and-latency-test.py script

  • Make sure the pod that mounts the storage that you wish test has python installed in it:
oc -n <namespace> exec <pod_name> -- bash -c 'python V'
Python 3.12.13
  • If python isn't available in the container (or not installed into the $PATH) you may receive the following error:
bash: line 1: python: command not found
command terminated with exit code 127
  • If Python is available inside the container, download this python script either via the browser or using curl, like this:
curl -L -v -o disk-iops-and-latency-test.py https://ibm-mas.github.io/mas-performance/pd/download/disk-iops-and-latency-test.py
  • Make sure the script is executable:
chmod +x disk-iops-and-latency-test.py
  • Copy the script to the /tmp directory inside the container:
oc -n <namespace> cp disk-iops-and-latency-test.py <pod_name>:/tmp/disk-iops-and-latency-test.py`
  • Determine which file system inside the container is mounting the storage you wish to test:
oc -n <namespace> exec <pod_name> -- bash -c 'mount'

  • Run the python script using oc exec specifying the following parameters:

    • The full path to the python script on the container; example:
    /tmp/disk-iops-and-latency-test.py
    • The file you wish to write to test the disk characteristics. This should be written to a directory in the file system that mounts the physical volume you wish to test. Example:
    /jms/write-test.out
    • The number of write iterations (default is 1000)
    • The size of data written per iteration (default is 4096 bytes)
    • Enable/disable Direct I/O: (optional): 1 or 0 whether you want to disable Direct I/O (some file systems don't support Direct I/O in which case you must pass in 0 for this parameter to make the script work).

  • Full example:

oc -n <mas_manage_namespace> exec -it <manage_jms_pod_name> -- /tmp/disk-iops-and-latency-test.py /jms/write-test.out 1000 4096 1
  • When the script executes successfully, you should see output similar to this:
DISK WRITE PERFORMANCE RESULTS
============================================================

IOPS Metrics:
Write IOPS:           2,076.37 ops/sec
Throughput:           10.28 MB/s
Total operations:     1,000
Total time:           0.38 seconds
Total data written:   3.91 MB

Latency Metrics (milliseconds):
Average:              0.480 ms
Median (P50):         0.499 ms
Std Deviation:        0.064 ms
Minimum:              0.342 ms
Maximum:              1.054 ms

Latency Percentiles:
P50 (median):         0.500 ms
P95:                  0.549 ms
P99:                  0.601 ms
P99.9:                1.054 ms
============================================================
  • Fields to pay special attention are:
    • "Throughput" (under "IOPS Metrics")
    • "Average" and "Median" values under "Latency Metrics" (for JMS pods, for example)