Sasiotest Utility

When troubleshooting performance problems, you need to know the throughput rates of any file system that SAS uses. The Sasiotest utility performs the following actions:
  • measures the I/O behavior of the system under defined loads
  • opens files and reads and writes data, similar to SAS I/O
  • creates and writes files to the file system that is being tested, and reads them to test Write and Read performance
  • writes an output file that captures elapsed real time and I/O rate, expressed as megabytes per second
  • reads random pages
  • can run several I/O tests concurrently to overload the file system and determine its performance
The following information relates to how the Sasiotest utility operates on Windows:
  • runs on 32-bit and 64-bit Windows systems
  • is delivered with SAS and is installed in the SASHOME directory at \SASHome\SASFoundation\9.4\sasiotest.exe
  • is a stand-alone program, and can be launched from a command prompt window
  • uses the Windows APIs Writefile(), Readfile(), and Closefile()
  • supports the Readfilescatter() and Writefilescatter() APIs for Scatter-Gather I/O testing outside the file cache
  • can be copied and used as a stand-alone executable on any system with or without SAS
  • can be copied and used on a machine that has previous SAS releases
For information about how SAS performs I/O and the minimum I/O recommendations for SAS file systems, see the SAS papers available at The papers outline recommended I/O metrics for file systems that support SAS deployments, and they identify guidelines that can help tune I/O characteristics for optimal SAS performance. If you are testing your file system throughput to solve an existing performance problem, see especially the following papers about performance-problem resolution using SAS logs in combination with host monitors. Select Performance monitoring and troubleshooting to access the following papers:
  • Solving SAS Performance Problems: Employing Host Based Tools
  • A Practical Approach to Solving Performance Problems with SAS
  • SAS Performance Monitoring - A Deeper Discussion