How to analyse FIO output

Storage performance testing plays a vital role in understanding the capabilities of your storage system. When using tools like Fio (Flexible I/O Tester) to evaluate performance, analyzing the generated output is crucial. This guide will walk you through the process of analyzing Fio output to gain insights into your storage system's performance.

Step 1: Run Fio Test: Begin by running the Fio test using your desired configuration file. For instance, if your configuration file is named random-read.fio, execute the following command:

fio random-read.fio

 

Step 2: Understand the Output: Fio provides both human-readable and machine-readable output. While the human-readable output is displayed in the terminal during testing, the machine-readable output is saved in a JSON file. This JSON output is well-suited for detailed analysis.

Step 3: Parsing JSON Output: To extract specific metrics from the JSON output, tools like jq can be helpful. For instance, to retrieve the mean IOPS of read operations, use:

fio random-read.fio --output=result.json
jq '.jobs[0].read.iops_mean' result.json

 

Step 4: Metrics to Analyze: Key metrics to analyze include:

• iops: Input/Output Operations Per Second.
• bw: Bandwidth in bytes per second.
• lat: Latency metrics, such as lat_ns for nanosecond latency.
• slat, clat, and latency percentiles: These provide insights into different latency components.

 

Step 5: Graphing and Visualization: Visualizing metrics over time using tools like Excel or Gnuplot can reveal performance trends. This helps identify potential bottlenecks or improvements in your storage system.

 

Step 6: Comparing Tests: When conducting multiple tests with varying configurations, comparing their outputs can highlight performance differences. This aids in pinpointing optimization opportunities.

 

Step 7: Experimentation and Iteration: Fio offers numerous configuration options. Experiment with different settings to understand how your storage system behaves under various workloads.

In conclusion, effectively analyzing Fio output involves running tests, extracting relevant metrics, visualizing data, and making informed decisions based on your storage system's behavior. By following these steps, you can unlock valuable insights into your storage system's performance and make informed decisions about optimizations and configurations.