Simple hardware check using PowerShell

This PowerShell script reviews a few common areas of concern for SQL Server. The script checks for power management mis-configuration, high committed memory, and disk latency. Power management settings negatively affect the server performance by more than 20%. Finding and resolvi

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  • How did you come with 25 ms for disk latency?
    2 Posts | Last post August 19, 2016
    • Hi Daniel,
      Never seen 25 ms. Why 25, not 20? Any good source for all counters important for SQL Server?
    • 25 ms is generally accepted as "slow". This is what we taught in PFE at Microsoft. Like anything in SQL Server you could say "It depends". Many customers may have latency of 50 ms or more and see no problem with it. On the other hand I've been to a handful of clients where they felt pain when disk latency was higher than 15 ms. 
      Consider the following when looking at your storage: Latency of 25 ms is slower than a 7200 RPM disk. Expect that a 15000 RPM disk is < 8 ms round trip with the average IO latency for this type being 4 to 6 ms. A 1.44 floppy has an average latency of 300 ms. PCIe storage is < 1 ms.
      There are many factors in reviewing disk latency. This code sample was created to help draw attention to items that need more research. Check out my SQL Books Online article on disk for more information here:
      I hope that helps!