Calculating unreserved CPU capacity via ARIA host metrics

Products

• VMware Aria Suite

Issue/Introduction

ESXi available CPU resources for reservation require calculations to account for system overhead and VM's with existing reservations that is not a metric directly available in Aria system metrics

Environment

8.x

Resolution

The following host system CPU metrics can be utilized together to calculate the exact available unreserved capacity within ARIA

Host System Metrics > CPU

• CPU|Total Capacity (MHz)
• CPU|Overhead (MHz)
• CPU|Reserved Capacity (MHz)

Calculation:

CPU|Total Capacity - ( CPU|Overhead + CPU|Reserved Capacity ) = Unreserved CPU available for VM Reservations

The above can also be verified via CLI by connecting to the host and running the following command:

vsish -e get /sched/groups/4/stats/capacity

Example Output:

group-capacity {
cpu-reserved: 58000 MHZ
cpu-unreserved:67932 MHz   <================== Available for a VM to request at power on for its RESERVATION
mem-reserved:67645012 KB
mem-unreserved: 669352008 KB