vSphere collects performance data on managed objects. Performance metrics organize this data into the following categories:

Metric Groups

Metric group

Description

Cluster Services

Performance statistics for clusters configured by using VMware DRS (distributed resource scheduler), VMware HA (high availability), or both.

CPU

CPU utilization per host, virtual machine, resource pool, or compute resource.

Datastore

Statistics for datastore utilization

Disk

Disk utilization per host, virtual machine, or datastore. Disk metrics include I/O performance (such as latency and read/write speeds), and utilization metrics for storage as a finite resource.

Management Agent

Memory swap statistics per COS.

Memory

Memory utilization per host, virtual machine, resource pool, or compute resource. The value obtained is one of the following:

For virtual machines, memory refers to guest physical memory. Guest physical memory is the amount of physical memory presented as a virtual-hardware component to the virtual machine, at creation time, and made available when the virtual machine is running.

For hosts, memory refers to machine memory. Machine memory is the RAM that is installed in the hardware that comprises the ESX/ESXi system.

Network

Network utilization for both physical and virtual network interface controllers (NICs) and other network devices, such as the virtual switches (vSwitch) that support connectivity among all components (hosts, virtual machines, VMkernel, and so on).

Power

Energy usage statistics per host.

Storage Adapter

Data traffic statistics per HBA.

Storage Path

Data traffic statistics per path.

System

Overall system availability, such as system heartbeat and uptime. These counters are available directly from ESX and from vCenter Server.

Virtual Machine Operations

Virtual machine power and provisioning operations in a cluster or datacenter.

Each metric group contains one or more data counters (Data Counters). vCenter Server collects and stores data for all counters. However, the counters that are available for customizing a performance chart depend on the Statistics Level setting (Statistics Levels, and the selected time period (Real Time, Past Day, and so on).

Calculations for all metrics are for the duration of the data collection cycle. Collection cycle durations are specified by the Statistics Interval > Interval Duration setting.

You can use the vShpere Web Services SDK to query vCenter Server and get statistics for all counters. The VMware vSphere API Reference contains detailed information about all data counters.