Virtual machines exist on hosts within the network. Hosts are added to the VirtualCenter environment. The VirtualCenter server automatically discovers and adds all the virtual machines contained within that host to the VirtualCenter environment.
The figure below illustrates the process for adding a host to VirtualCenter. Refer to Abbreviations for a description of abbreviations.
A host can be added to only one VirtualCenter server.
- Ensure a communication channel through a firewall, if needed.
If any host in the VirtualCenter environment is on the other side of a firewall, all hosts must open port 902 to enable incoming and outgoing traffic. Refer to Connecting to VirtualCenter Through a Firewall for additional information.
- From the VirtualCenter client, display the inventory panel and select the appropriate farm.
Click the Inventory option in the navigation bar. Expand the inventory as needed, and click the appropriate farm.
- Start the Add Host wizard.
Select the appropriate farm, and select New Host from the main or right-click popup menu.
- Confirm proceeding with the Add Host Wizard. Click Next.
- Enter the host connection settings.
Type the name of the host in the Hostname field. Enter the username and password for a user account that has administrative privileges on the selected host. Click Next to continue.
Refer to your ESX Server or GSX Server documentation for information on changing the port number if needed.
VirtualCenter does the following:
- Connects to the host.
- Verifies that the host is not already being managed. If it is already being managed on another farm, VirtualCenter displays an information message.
- Reads the number of CPUs on the host and allocates the appropriate number of licenses. The number of CPUs is stored in the VirtualCenter database and is verified upon each host reconnect and VirtualCenter start-up.
- Verifies that the host version is supported. If it is not, VirtualCenter checks if the current version can be upgraded. If the host version can be upgraded, VirtualCenter prompts you to perform an upgrade.
- Imports existing virtual machines.
- If you are adding an ESX Server: enable VMotion for the host, as needed.
To enable VMotion:
Click Yes. Enter the network adapter, IP address, and gateway for the host. This is the information for the migration network, including which NIC it uses, and its IP address and gateway. The migration network should be a separate network.
If VMotion is enabled, VirtualCenter checks for a migration license and adds it to the host information.
To leave VMotion disabled: Click No.
Click Next to continue.
Refer to Enabling VMotion for additional information.
- If you are adding a GSX Server: identify the VirtualCenter user.
When adding a GSX Server host to a farm through the Add Host wizard, VirtualCenter requires two user names in the following order:
- The user specified in step 5 to add the host. This is the user who has administrator privileges on the GSX Server host.
- The VirtualCenter user.
VirtualCenter impersonates the VirtualCenter user on the managed host when accessing files and performing management and provisioning operations on a host. This user may be the same or different than the administrator user specified in step 5. This user must have sufficient privileges to access the physical resources that the virtual machines use, such as files and networks.
Note: At any given point in time, there is only one username/password that
VirtualCenter stores for a given host. That is the account for the VirtualCenter
user. At step 5, you specify the administrator user that proves that you have the
permission to work in VirtualCenter and on the host. If at this step, you choose
different (maybe non-administrator) user, you are essentially saying, "Now that I
have proven that I am for real, connect to that host and run all the virtual
machines as this other user." If you choose to not specify a different user account
here, you are essentially saying, "I want to connect to this host and perform
VirtualCenter operations as this administrator".
- Complete the Add Host wizard, click Finish.
The Add Host wizard searches the network for the specified host, performs the discovery to identify all the virtual machines on the host, and if possible, connects the host. If the wizard cannot connect the host, the host is not added to the inventory. If the wizard can connect to the host but for some reason cannot remain connected to the VirtualCenter server, the host is added, but is in an disconnected state. This occurs for example if the host is already being managed by another VirtualCenter server.
If you click Cancel, the host is removed from the VirtualCenter inventory.
If you are adding a GSX Server host: all virtual machines on that host are listed. This includes virtual machines that are designated as private within GSX Server. Though VirtualCenter can manage private virtual machines, only users with an appropriate VirtualCenter designated permission role can perform actions on a private virtual machine.
Prior to using the migration feature or adding new virtual machines on a GSX Server host, network labels must be assigned to each network interface in each GSX Server host. Prior to configuring network labels, the GSX Server must be added to the VirtualCenter server.
VirtualCenter allows the management of GSX Server hosts, which is a powerful new feature. But VirtualCenter is centered around the concept of virtual machine migration, while the normal GSX Server console is centered around a single host. This different emphasis causes the two products to have very different views of virtual network connections. In VirtualCenter, the most important thing about a virtual network interface is what network it connects to, because that limits what possible hosts the virtual machine containing it could migrate to.
The normal GSX Server methods for specifying network interfaces (Bridged, NAT, Host-Only, or Custom) do not apply in the VirtualCenter environment. For example:
- A VirtualCenter-managed farm might include three physical networks:
- One which connects through a firewall to the Internet
- One which is internal to the server room
- One which is dedicated for connection to networked storage.
- On a GSX Server host, these networks might be set up as
- the bridged network,
- a custom network on vnet4,
- a network not even visible to the virtual machines directly
- On a second GSX Server host, the network might be set up as
- only one network card, connected to the server-room network only. On this host the network would be a bridged network.
Note: that in this example, knowing that a network is bridged is of no value at all in
determining what network it is.
VirtualCenter must be able to identify the actual network that the interface connects to. This has to be manually set by someone who knows the physical connections and GSX Server custom settings.
Specifically, VirtualCenter provides a method by for assigning a label or name to each network connection on each host. This network name becomes a global identifier for the actual network. In the example above, the administrator might choose to call the first network the main or corporate or intranet network, the second network the server link network, and the third network the storage network.
These labels are used by VirtualCenter when a virtual machine is migrated. The virtual NICs are matched up to the networks on the new host by the network names.
So in order to provision network cards to virtual machines on GSX Server hosts using VirtualCenter, you must name the network interfaces on each GSX Server host. To do this, use the management interface. This naming need only be done once per network per host.
To specify network labels for all the virtual NICs in your GSX Server virtual machines:
This need only be done once. Refer to your GSX Server documentation for additional information.
- Register the GSX Server as a host with VirtualCenter.
- Log into the management interface as root and/or Administrator.
- Click the Options tab.
- Click the Network connections link.
A window displays a list of network adapters and network labels. On Linux systems all possible VMnets are displayed. On Windows systems only the adapters and labels that are enabled are displayed.
- Assign or change the labels as desired and click OK, or click Cancel to not accept the change.
To configure a virtual machine to use a named network:
- From the management interface, select the Hardware tab.
- Select either Add a New, or Edit an Existing network adapter.
- Select Network Connection then click the Named radio button.
- Select the appropriate network from the pull down menu.
Existing virtual machines on your GSX Server hosts continue to work, naming your networks does not modify the existing virtual machines in any way. Their virtual NICs continue to be read as bridged, NAT, etc. If you edit the virtual machine configuration under VirtualCenter, you have the option of changing them from their current value to a network name value. Only VirtualCenter specific name options are offered. The GSX Server-specific values, such as Bridged, NAT, are not valid VirtualCenter options.
If you migrate the virtual machines to a different GSX Server host without changing the NIC settings, the GSX Server-style name are applied to the new host's environment. This might result in a sudden change of network topology.
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