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Storing and Replicating Images Using DFS

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Applies To: Windows Server 2008, Windows Server 2008 R2

This section outlines the tools and topology configurations associated with the Distributed File System (DFS) role service in the File Services server role of Windows Server 2008 and Windows Server 2008 R2. You may have to update your Active Directory Domain Services (AD DS) schema to use DFS to manage multiple Windows Deployment Services servers. Any issues pertaining to AD DS, updates to an AD DS schema, and AD DS maintenance and best practices are outside the scope of this document. For more information about the steps in this topic, see one of the following:

Storing Files on Another Server

You can store install images on another server (not a Windows Deployment Services server) using DFS and then deploy the images by using Windows Deployment Services. This functionality provides three main benefits:

  • Load balancing. Clients can be directed to computers other than the Windows Deployment Services server to download the image.

  • Simplified administration. You can use DFS Replication to propagate changes you make to an image to other distribution points.

  • Site Awareness. Client will be directed first to the closest in a multi-site environment.

Note

You cannot redirect the boot directory (that is, \<server>\reminst\boot) using DFS. If you do, Windows Deployment Services will not start.

To configure DFS Namespaces for install images:

  1. Install and configure Windows Deployment Services.

  2. Install DFS Management and related services, from Server Manager. To do this, use the Add Roles Wizard to select the File Services role, and then select the Distributed File System role service.

  3. Create a file share on a secondary server. Grant permissions to the Windows Deployment Services server’s computer account. For example, if the server is called MyWDSServer, grant read/write permissions to MyWDSServer$.

  4. Create a new namespace by using DFS Management (unless you have an existing namespace that you would like to use). For example, \\fileserver\MyNamespace for a stand-alone namespace or \\corp.woodgrovebank.com\MyNamespace for a domain-based namespace.

  5. Add a new folder to the namespace and create an image group on the Windows Deployment Services server as the folder target. For example, create \\MyServerOrDomain\MyNamespace\ImageGroup in DFS Management, and specify \\MyWDSServer\RemoteInstall\images/\DFSImageGroupName as a folder target for that folder.

  6. Add images to the Windows Deployment Services server.

  7. Verify that the content appears when you connect to \\MyServerOrDomain\MyNamespace\ImageGroup.

  8. Repeat this procedure for additional image groups.

Replicating Images

DFS Replication is a replication engine that you can use to replicate images between Windows Deployment Services servers. DFS Replication can decrease the total cost of ownership by making it possible for you to manage images from a single server in the environment. Changes can then be propagated to other servers without requiring interaction. A best practice is to create a single, master Windows Deployment Services server and make all modifications to images on this server by using the Windows Deployment Services management tools and the tools included in the Windows AIK. Then wait for your changes to finish replication. You can view replication status by creating a replication report (see Create a Diagnostic Report for DFS Replication). To prevent replication conflicts, avoid modifying or servicing the same image from multiple servers at the same time, or make the replicated folder read-only on all replication group members except Windows Deployment Services.

To configure DFS Replication for install images:

  1. Install and configure Windows Deployment Services.

  2. Install DFS Management and related services, from Server Manager. To do this, use the Add Roles Wizard to select the File Services role, and then select the Distributed File System role service.

  3. Create and configure a replication group for the RemoteInstall folder or its subfolders (for example, \boot and \images). If you are replicating RemoteInstall subfolders, you must exclude the \Mgmt and \Tmp folders. If your server is running Windows Server 2008 R2, note that you must also exclude the \Stores directory, which contains server-specific information (including the driver store) that cannot be used by remote Windows Deployment Services servers.

  4. Configure the BCD refresh policy by running the following command (see below for details about the options): WDSUTIL /set-server /BcdRefreshPolicy /Enabled:yes /RefreshPeriod:<time in minutes>

Note

If you do not configure this policy or if your refresh period is too long, network boots will fail with the following error message: “The boot selection failed because a required device is inaccessible.” (0xc000000f). This is because the server must be regenerate the corresponding BCD before a client can receive a boot image from the server.

Option Explanation

/BcdRefreshPolicy

Causes the server to regenerate BCD stores in the \Tmp folder for all boot images.

/RefreshPeriod

Determines how often the boot images are regenerated. This value is required so that any changes that you make to your boot images on the master server are reflected in the boot menus that clients receive from remote servers. If you do not make changes to boot images very often, it is okay to have a larger value. If you make changes to boot images often or if you want changes to propagate quickly, set this to a lower value. However, be careful when setting a low value. BCD generation causes CPU and disk overhead on the Windows Deployment Services server. Configuring a small value can cause performance problems on the server. A good default value is 30 minutes.