Managed components are objects in your virtual and physical infrastructure on which you can place permissions, monitor tasks and events, and set alarms. You can group most managed components by using folders to more easily manage them.

All managed components, with the exception of hosts, can be renamed to represent their purposes. For example, they can be named after company departments or locations or functions. vCenter Server monitors and manages the following components of your virtual and physical infrastructure:


A collection of ESX/ESXi hosts and associated virtual machines intended to work together as a unit. When you add a host to a cluster, the host’s resources become part of the cluster’s resources. The cluster manages the resources of all hosts.

If you enable VMware DRS on a cluster, the resources of the hosts in the cluster are merged to allow resource balancing for the hosts in the cluster. If you enable VMware HA on a cluster, the resources of the cluster are managed as a pool of capacity to allow rapid recovery from host hardware failures.See the Resource Management Guide.


Unlike a folder, which is used to organize a specific object type, a datacenter is an aggregation of all the different types of objects needed to do work in virtual infrastructure: hosts, virtual machines, networks, and datastores.

Within a datacenter there are four separate hierarchies.

Virtual machines (and templates)

Hosts (and clusters)



The datacenter is the unit of virtualization (the namespace) of networks and datastores. Within a datacenter, you cannot have two objects (for example, two hosts) with the same name but you can have two objects with the same name in different datacenters. Virtual machine names need not be unique within the datacenter, but must be unique within each virtual machine folder.

If two virtual machines connect to networkA, they are connected to the same network. Rules are different across datacenters. Theoretically, the same physical network can appear in two datacenters and be called two different names. Or networkA might have one meaning in datacenterA and a different meaning in datacenterB. Moving objects between datacenters can create problems or, at least, unpredictable results.

To have a single namespace (that is, a single datacenter) for all networks and datastores, use folders within the datacenter to organize the networks and datastores. To have separate namespaces (separate datacenters) for networks and datastores, create two datacenters.


A virtual representation of combinations of underlying physical storage resources in the datacenter. A datastore is the storage location for virtual machine files. These physical storage resources can come from the local SCSI disk of the server, the Fibre Channel SAN disk arrays, the iSCSI SAN disk arrays, or Network Attached Storage (NAS) arrays. Datastores hide the idiosyncrasies of the storage options and provide a uniform model for various storage products required by virtual machines.


A top-level structure for vCenter Server only. Folders allow you to group objects of the same type so you can easily manage them. For example, you can use folders to set permissions across objects, to set alarms across objects, and to organize objects in a meaningful way.

A folder can contain other folders, or a group of objects of the same type: datacenters, clusters, datastores, networks, virtual machines, templates, or hosts. For example, one folder can contain hosts and a folder containing hosts, but it cannot contain hosts and a folder containing virtual machines.

The datacenter folders form a hierarchy directly under the root vCenter Server and allow users to group their datacenters in any convenient way. Within each datacenter is one hierarchy of folders with virtual machines and templates, one with hosts and clusters, one with datastores, and one with networks.


The physical computer on which the virtualization platform software, such as ESX/ESXi, is installed and all virtual machines reside. If the vSphere Client is connected directly to an ESX/ESXi host, only that host is available for management.


When vCenter Server refers to a host, this means the physical machine on which the virtual machines are running. All virtual machines within the VMware vSphere environment are physically on ESX/ESXi hosts. The term host in this Help system refers to the ESX/ESXi host that has virtual machines on it.


A set of virtual network interface cards (virtual NIC), virtual switches (vSwitch), and port groups that connect virtual machines to each other or to the physical network outside of the virtual datacenter. All virtual machines that connect to the same port group belong to the same network in the virtual environment, even if they are on different physical servers. You can monitor networks and set permissions and alarms on port groups.

Resource pools

A structure that allows delegation of control over the resources of a host. Resource pools are used to compartmentalize all resources in a cluster. You can create multiple resource pools as direct children of a host or cluster and configure them. Then delegate control over them to other individuals or organizations. The managed resources are CPU and memory from a host or cluster. Virtual machines execute in, and draw their resources from, resource pools.

vCenter Server provides, through the DRS components, various options in monitoring the status of the resources and adjusting or suggesting adjustments to the virtual machines using the resources. You can monitor resources and set alarms on them.


A master copy of a virtual machine that can be used to create and provision new virtual machines.

Virtual machines

A virtualized x86 or x64 personal computer environment in which a guest operating system and associated application software can run. Multiple virtual machines can operate on the same managed host machine concurrently.


VMware vApp is a format for packaging and managing applications. A vApp can contain multiple virtual machines.