Planning for the VMM Library

Applies To: Virtual Machine Manager 2008, Virtual Machine Manager 2008 R2, Virtual Machine Manager 2008 R2 SP1

The System Center Virtual Machine Manager (VMM) 2008 library is a catalog of resources you can use to create and configure virtual machines. The library contains files stored on library shares, and it contains operating system, hardware, and template configurations stored in the VMM database. Library resources are added, created, used, and managed in Library view. Using the VMM library helps promote re-use of approved images and configurations.

To be used in VMM, file-based resources must be added to the library by storing the files on a library share of a library server.

Virtual machine templates, hardware profiles, and guest operating system profiles are used in creating uniform virtual machines. These configurations are managed in Library view, but are stored in the VMM database and not represented by physical configuration files.

Virtual machines that are not in use and stored in the library are displayed in Library view. However, the configuration file (.vmc) and hard drive file (.vhd) for a stored virtual machine are not displayed in the library because these files cannot be used to create or configure new virtual machines.


Virtual Machine Manager does not support file servers configured with the case-insensitive option for Windows Services for UNIX as the Network File System case control is set to Ignore. For more information about Network File System case control, see Windows Services for UNIX 2.0 NFS Case Control (

Library Servers

By default, VMM contains a single library server and a single library share, which Setup creates on the VMM server. The VMM server always remains the default library server.

During VMM server setup, you can choose to create a new default library share on the default library server or specify an existing share to be used as your default library share.


After Setup is complete, you cannot remove or relocate the default library server or its library share. So give careful consideration to its location before installing the VMM server.

The default library server might be the only library server you ever need. However, you can add more library servers and library shares based on your current business needs and objectives, and to scale out as your virtual environment grows. Each library server can have multiple library shares. To enhance performance and reduce network traffic during virtual machine creation, it’s important to store the files that you use to create virtual machines near the hosts you will use to stage virtual machine creation.

To make a library server highly available, VMM 2008 supports adding highly available file servers on a failover cluster created in Windows Server 2008 Enterprise Edition or Windows Server 2008 Datacenter Edition. VMM 2008 R2 also supports adding highly available file servers on a failover cluster created in Windows Server 2008 R2 Enterprise Edition or Windows Server 2008 R2 Datacenter Edition.


After you update the nodes in a failover cluster that serves as a highly available library server from Windows Server 2008 to Windows Server 2008 R2, you will need to update the VMM agent on each node of the highly available file server individually. In Administration view of the VMM Administrator Console, expand Managed Computers. Then select each server that is included in the highly available library server, and click Update Agent in the Actions pane.


VMM does not support using a failover cluster that contains the VMM server as a highly available library server.

If you use a SAN, it is a best practice to have a library server on the same SAN as the virtual machine hosts that use the library server. By doing so, the library server and the hosts can all access the same logical unit numbers (LUNs) on the SAN, which allows you to make faster file transfers. For more information, see Configuring a SAN Environment for VMM.

If you connect to a library server from hosts across a LAN network, your library server should be as close to the hosts as possible on the network. It is a best practice to connect all computers in a VMM configuration with at least a 100-MB Ethernet connection. Using a gigabit Ethernet connection will improve performance. Using a gigabit connection, combined with a more powerful processor than the recommended processor on the VMM server, will further improve performance.

Library Groups

As you add more library servers, you can create library groups to help you organize library servers in whatever way best meets your needs. You can also use library groups to align your library servers with the host groups that use the resources on the library server. It is a best practice to align each library server with the host group that uses the resources on that library server. The library group Properties dialog box makes this alignment easy to do by displaying the host groups tree in the Library group drop-down list.

Aligning library servers with host groups is especially beneficial when your library server is connected to the same SAN as the hosts in a host group. By using descriptive library group and host group names (such as, SAN_A), you can then readily identify which library servers and hosts are connected to the same SAN and therefore can take advantage of faster file transfers on the SAN. When you are selecting an object (template, virtual hard disk, or virtual machine) to create a new virtual machine, you can filter the objects by a specific library group name. And then, when you are selecting a host on which to place the virtual machine, you can filter the available hosts by the aligned host group name.

Distributed Resources

For geographically-disperse organizations, VMM supports the use of distributed VMM library servers that are managed by a centralized VMM server. For example, if you have branch offices in multiple locations, users in those locations can build virtual machines by using resources from a local library server instead of copying multi-gigabyte files from a centralized library server over a wide area network (WAN). Having distributed VMM libraries can also help ensure the availability of files during WAN outages or server failures.


VMM 2008 does not provide a method for replicating physical files in the VMM library or metadata for objects that are stored in the VMM database. Physical files must be replicated outside of VMM and metadata must be transferred by using scripts or other means. VMM does not support DFS Namespaces (DFSN), formerly known as Distributed File System (DFS), or DFS Replication (DFSR).

Library Share Permissions

To view or run scripts on a library share or to open and explore a library share, the VMM administrator must have Read permission on the library share.

See Also


Planning for Branch Offices or Remote Sites
Managing the VMM Library