A lot of VMware vSphere architects and engineers are designing their vSphere clusters for some overbooking ratios to define some level of the service (SLA or OLA) and differentiate between different compute tiers. They usually want to achieve something like
- Tier 1 cluster (mission-critical applications) - 1:1 vCPU / pCPU ratio
- Tier 2 cluster (business-critical applications) - 3:1 vCPU / pCPU ratio
- Tier 3 cluster (supporting applications) - 5:1 vCPU / pCPU ratio
- Tier 4 cluster (virtual desktops) - 10:1 vCPU / pCPU ratio
Before vSphere 6.5 we have to monitor it externally by vROps or some other monitoring tool. Some time ago I have blogged how to achieve it with PowerCLI and LogInsight - ESXi host vCPU/pCPU reporting via PowerCLI to LogInsight.