Home > Workload Solutions > SQL Server > Best Practices > AMD-Based SQL Server Best Practices on Dell PowerEdge R740 and PowerMax 2000 > Storage Best Practices > Day Three Best Practices > VMware vSphere: Virtual Machine Latency Sensitivity
Many database workloads are sensitive to storage performance. In this best practice, the virtual machine latency sensitivity has been changed to optimize performance.
Category | PowerMax Storage |
Product | VMware vSphere Virtual Machines |
Type of best practice | Performance Optimization |
Day and value | Day 3, Fine-tuning |
Overview
VMware vSphere provides the ability to adjust latency sensitivity to optimize low latency database workloads and similar applications. We used the default value for latency sensitivity (Normal) for our baseline test. The default latency sensitivity optimizes storage performance for throughput.
For this best practice, we recommend changing the latency sensitivity to High. Changing the latency sensitivity to High causes ESXi to optimize I/O operations for improved storage latency. This latency sensitivity change was completed for all the virtual databases.
Recommendation
Changing the latency sensitivity for the virtualized databases showed a minor improvement for these performance metrics:
Although there were no significant performance gains in our validation tests, this does not mean other workloads would not benefit from setting the VM latency sensitivity to High. In our tests, all four databases were set to a latency sensitivity of High — that meant all databases were configured the same way, which is not how most systems will be configured. Ideally, there will be a few critical systems with a latency sensitivity of High and others that are set to Normal or Low, which could yield a greater performance gain for the production systems.
We recommend virtual machine latency sensitivity as a Day 3, Fine-tuning activity. Consider changing the latency sensitivity to High for the SQL Server production virtual machines to optimize storage performance.
Implementation Steps
Requirements:
Versions of ESXi 6.7 and later require complete CPU and memory reservation to power on a VM with hardware version 14 when latency sensitivity is set to High. For more information, see Adjust Latency Sensitivity.
Additional Resources