Understanding Events

An Event is a data object type that contains information about state changes of managed entities and other objects on the server. Events include user actions and system actions that occur on datacenters, datastores, clusters, hosts, resource pools, virtual machines, networks, and distributed virtual switches. For example, these common system activities generate one or more Event data objects:

• Powering a virtual machine on or off
• Creating a virtual machine
• Installing VMware Tools on the guest OS of a virtual machine
• Reconfiguring a compute resource
• Adding a newly configured ESXi system to a vCenter Server system

In the vSphere Client, information from Event objects generated on a standalone ESXi hosts displays in the Events tab. For managed hosts, information from Event objects displays in the Tasks & Events tab.

Persistence of Event objects depends on the system setup.

• Standalone ESXi hosts – Event objects are not persistent. Events are retained only for as long as the host system’s local memory can contain them. Rebooting a standalone ESXi host or powering off a virtual machine removes Event objects from local memory.

  A standalone ESXi host might keep about 15 minutes worth of Event data, but this can vary depending on the processing load of the host, the number of virtual machines, and other factors.

• Managed ESXi systems. Event objects are persistent. Managed ESXi systems send Event data to the vCenter Server system that manages them, and the vCenter Server system stores the information its database.

You can use the event sample applications included in the SDK package with either managed or standalone ESXi systems and with vCenter Server systems.

Using an EventHistoryCollector, you can obtain information about these objects as they are being collected on a specific ESXi system, or from a specific historical period from the database. See Using an EventHistoryCollector.