A host is a virtualization platform that supports virtual machines. A vCenter Server managed host is a host that is registered with vCenter Server.

The task of managing a host is accomplished through the vSphere Client. This vSphere Client can be connected either directly to an ESX/ESXi host or indirectly to hosts through a connection to a vCenter Server system.

When ESX/ESXi hosts are connected to the vSphere Client directly, you manage them individually as standalone hosts. Most of the host configuration and virtual machine configuration features still apply. Features that require multiple hosts, such as migration with VMotion of a virtual machine from one host to another, are not available through the standalone host connection.

When ESX/ESXi hosts are managed by vCenter Server, they are added to the vSphere environment through a vSphere Client connected to a vCenter Server system. Managed hosts are hierarchically placed in datacenters, folders, or clusters under the root vCenter Server system.

Caution

If an ESX/ESXi host is connected with a vCenter Server system and you attached a vSphere Client to manage the ESX/ESXi host directly, you receive a warning message but are allowed to proceed. This might result in conflicts on the host, especially if the host is part of a cluster. This action is strongly discouraged.

All virtual machines on managed hosts are discovered and imported into vCenter Server. When you add multiple managed hosts, vCenter Server identifies any naming conflicts that exist between virtual machines and alerts the system administrator, who can then rename virtual machines as necessary.

When vCenter Server connects to a managed host, it does so as a privileged user. The individual vSphere Client user does not necessarily need to be an administrative user on the managed host.