Precise Performance Monitoring with vSAN IOInsight


Delivering desired levels of performance and availability is a primary requirement in any environment. While availability requirements are easier to maintain, performance monitoring requires a better understanding of various infrastructure components. This is incredibly difficult in larger environments with numerous workloads. VMware vSAN has continuously evolved monitoring capabilities with new features and enhancements to provide insights into workload performance. vSAN 7 Update 1 exemplifies these enhancements with a new feature called IOInsight that renders advanced performance metrics and workloads characteristics through the vCenter UI on-demand.

IOInsight allows administrators to monitor a range of performance metrics and workload characteristics; this includes:

  • I/O Ratio – Read/Write ratio, Sequential/Random ratio, and 4K Aligned/Unaligned ratio
  • I/O Size Distribution
  • I/O Latency distribution

IO Insight
All this, in addition to foundational metrics such as IOPS, throughput, and latency. These metrics provide a deeper understanding of workloads and help make finer adjustments to vSAN environments catered to the workloads.

Integrated within the vCenter UI

Performance troubleshooting commonly requires multiple tools, command-line expertise, and significant effort to collect appropriate information to determine the root cause. IOInsight simplifies troubleshooting efforts and is made easily consumable within the vCenter UI. Administrators can invoke IOInsight from the UI through a guided workflow to monitor a set of VMs or hosts. It gathers data from the chosen inventory objects and is run on-demand for a stipulated duration ranging from minutes to up to 24 hours per instance. You can identify each instance by the cluster name and timestamp or rename the sample for ease of use. The results can be viewed in real-time or accessed after data collection is complete. This saves time for the administrator and improves efficiency in Day-2 operations and monitoring.
IO Insight target

Granular monitoring capabilities

One of the challenges in monitoring performance is the significant amount of data accumulated over time. As a common practice to reduce collecting massive amounts of data, multiple data samples are rolled-up with time. However, this reduces the efficacy of the sample data since transient spikes are averaged. IOInsight takes a new and improved approach to gather statistics for a targeted set of inventory objects and a specific duration. This provides administrators information about every I/O for the associated objects, providing unprecedented accuracy and meaningful data for performance assessment.


Framework and usage

IOInsight requires the Performance Service to be enabled. It uses the Performance Service framework to gather and store data. It is important to note that IOInsight consumes compute and network resources from the cluster to perform its operations. Monitoring a large number of objects in a single instance can be resource intensive. There should be careful consideration in terms of the duration, the number of objects observed, and resource availability in the cluster before initiating IOInsight. Performance data is made available in the UI and purged when Performance Service is disabled in the cluster.



VMware vSAN has empowered administrators with various levels of performance monitoring capabilities. vCenter UI greatly simplifies Day-2 operations with essential metrics across all inventory objects. Integration with vRealize Operations Manager provides several dashboards and trends that can span multiple clusters providing a holistic view. With newer enhancements in vSAN 7 Update 1, vSAN IOInsight goes deeper to provide granular data for improved accuracy. These features and enhancements are made easily consumable through the UI, making an administrator’s life easy.

Next Steps

Here is a list of resources to help get familiarized with vSAN 7 Update 1:
Read the vSAN Datasheet
Take a technical deep dive at TechZone
Read more about vSAN 7 Update 1
Read the vSAN Technology Overview