Overview of the vSphere Guest API

The vSphere Guest API provides functions that management agents and other software can use to collect data about the state and performance of a VMware virtual machine. The Guest API provides fast access to resource management information, without the need for authentication.

The Guest API provides read-only access. You can read data using the API, but you cannot send control commands. To send control commands, use the vSphere Web Services SDK. For more information, see the VMware vSphere Web Services SDK Programming Guide and the VMware vSphere API Reference, which are available on the VMware developer support Web site.

The version number of this Guest API release is 9.0 to match the version number of VMware Tools.

Supported Guest Operating Systems

The vSphere Guest API software runs on most Windows or Linux guest operating systems supported by the various versions of ESXi.

See the VMware Compatibility Guide for a list of supported guest operating system versions. This guide is now located at http://www.vmware.com/resources/compatibility in Web format.

The Guest API does not support the following guest operating system environments:

■	Windows 95 and Windows 98.

■	Windows NT 4.0. For Windows NT 4.0 you must use Guest SDK 3.5, which you can find by going to http://www.vmware.com/support/developer/guest-sdk and selecting an old release.

Required Library Versions

To help you verify the minimum library version, the checksystem utility is bundled in the Guest SDK package for Linux guest OS systems. After you extract the Guest SDK, the utility is available in the GuestSDK/bin subdirectory. If the guest OS has a compatible glibc, the checksystem utility prints this message:

This version of GuestSDK is compatible with the version of glibc in this system.

If the Linux guest OS does not have a compatible glibc, this error message appears:

This version of GuestSDK requires version 2.5 or later of glibc. For this system,

use version 9.10.x of GuestSDK from https://www.vmware.com/support/developer/guest-sdk/

Virtual Machine Statistics

With the Guest API, you can monitor various statistics about the virtual machine. You can use this information to retrieve scheduling and resource usage information about the environment. With the help of these statistics, a virtual machine can immediately react to changes in its virtual environment at the application layer.

The information you can retrieve by using the vSphere Guest API includes:

■	Amount of memory reserved for the virtual machine.

■	Amount of memory being used by the virtual machine.

■	Upper limit of memory available to the virtual machine.

■	Number of memory shares assigned to the virtual machine.

■	Maximum speed of the virtual machine’s CPU.

■	Reserved rate at which the virtual machine is allowed to execute. An idling virtual machine might consume CPU cycles at a much lower rate.

■	Number of CPU shares assigned to the virtual machine.

■	Elapsed time since the virtual machine was last powered on or reset.

■	CPU time consumed by a particular virtual machine. When combined with other measurements, you can estimate how fast the virtual machine’s CPUs are running compared to the host CPUs.

Important The API uses a handle that provides access to the statistics. The handle also is a mechanism to determine whether the API can provide accurate information. (Certain events, such as migrating a virtual machine with VMotion™, temporarily make it impossible to provide accurate information.)