The Oversubscription recommendation identifies vSphere clusters that are oversubscribed.
- Cluster oversubscription is based on resource allocation and not on resource usage.
- If none of the resources in the cluster are saturated (Forecasted Saturation recommendation), oversubscription may not be a problem.
- Before modifying the cluster configuration or reducing resources, consider the following points:
- Review the peak loads for applications running on the VM. You can use Workspace > Analysis to understand the resource usage of the VM over a period.
For memory allocation of critical VMs, analyze performance data collected from inside the VM.
- If VMs are unused or idle, review the list of idle VMs in the capacity view and reclaim resources by removing the idle VMs from the cluster.
- To prevent future virtualization sprawl, best practices recommend for the vSphere administrator to define and enforce a process for the deployment of VMs.
- Cluster oversubscription might also be due to overallocation of resources to the VMs in the cluster. Review the list of overallocated VMs in the capacity view to determine if you want to continue to allocate those resources.
The recommended action specifies the resource identifiers of the clusters that can be reconfigured to reduce allocation, and VMs that can be deleted or allocated to another cluster.