Lesson 2: Administering Shared Folders by Using Dfs

The distributed file system (Dfs) allows for the creation of a single logical directory tree from a variety of physical systems. Although this technology was available in Microsoft Windows NT 4.0, the administrative tool for configuring the Dfs tree has been enhanced in Windows 2000. An understanding of how to use the Distributed File System console can help ensure an effective Dfs structure.

Dfs is a single hierarchical file system whose contents are distributed across the enterprise network. Dfs provides a logical tree structure for file system resources that can be anywhere on the network. Because the Dfs tree is a single point of reference, users can easily gain access to network resources regardless of the actual location of the resources. Dfs also facilitates administering multiple shared folders from a single location.

A Dfs share uses a tree structure that contains a root node and child nodes. To create a Dfs share, you must first create a Dfs root. Each Dfs root can have multiple child nodes beneath it, each of which points to a shared folder. The child nodes of the Dfs root represent shared folders that can be physically located on different file servers.

You can configure two types of distributed file systems:

• Stand-alone Dfs. Stores the Dfs topology on a single computer. This type of Dfs provides no fault tolerance if the computer that stores the Dfs topology or any of the shared folders that Dfs uses fail.
• Fault-tolerant Dfs. Stores the Dfs topology in Active Directory directory services. This type of Dfs allows child nodes to point to multiple identical shared folders for fault tolerance. In addition, it supports Domain Name System (DNS), multiple levels of child volumes, and file replication.

Navigating a Dfs-managed shared folder is easy because the user does not need to know the name of the server on which the folder is shared. This simplifies network access because users no longer need to locate the server where a specific resource is located on the network. After connecting to a Dfs root, users can browse and gain access to all resources below the root, regardless of the location of the server on which the resource is located.

Dfs also simplifies network administration. If a server fails, you can move a child node from one server to another without users being aware of the change. All that is required to move a child node is to modify the Dfs folder to refer to the new server location of the shared folders. Users continue to use the same Dfs path for the child node. Users can gain access to a shared folder through Dfs as long as they have the required permission to gain access to the shared folder.

A stand-alone Dfs root is physically located on the server to which users initially connect. The first step in setting up a stand-alone Dfs is to create the Dfs root.

To create a stand-alone Dfs root, use the Distributed File System console to start the Create New Dfs Root wizard. Table 8.1 describes the wizard options that you configure to create a stand-alone Dfs root.

Table 8.1 Creating a Stand-Alone Dfs Root

Option	Description
Select The Dfs Root Type	The type of Dfs root. Select Create A Standalone Dfs Root to store the Dfs topology on a single computer. A stand-alone Dfs root does not use Active Directory directory services and does not provide fault tolerance.
Specify The Host Server For The Dfs Root	The initial connection point for all resources in the Dfs tree, or the host server. You can create a Dfs root on any computer running Windows 2000 Server.
Specify The Dfs Root Share	A shared folder to host the Dfs root. You can choose an existing shared folder or create a new share.
Name The Dfs Root	A descriptive name for the Dfs root.

A fault-tolerant Dfs root can be created only on a domain controller. Active Directory directory services store each Dfs tree topology and replicate the topology to every participating Dfs root server. Because changes to a Dfs tree are automatically synchronized with Active Directory directory services, you can always restore a Dfs tree topology if the Dfs root is offline for any reason. You can implement fault tolerance at the file and content level by assigning replicas to a Dfs child node. Any branch node on the Dfs tree can be serviced by a set of replicated resources. If a client connection to one replica fails for any reason, the Dfs client attempts a connection to another. The Dfs client cycles through the replicas until an available one is found.

To create a fault-tolerant Dfs root, use the Create New Dfs Root wizard. Table 8.2 describes the wizard options you configure to create a fault-tolerant Dfs root.

Table 8.2 Creating a Fault-Tolerant Dfs Root

Option	Description
Select The Dfs Root Type	The type of Dfs root. Click Create A Domain Dfs Root. A domain Dfs root uses Active Directory directory services to store the Dfs tree topology and supports DNS naming, file replication, and fault tolerance.
Select The Host Domain For The Dfs Root	The initial connection point for all resources in the Dfs tree, or the host domain. A domain can host multiple Dfs roots.
Specify The Host Server For The Dfs Root	The initial connection point for all resources in the Dfs tree, or the host server. You can create a Dfs root on any computer running Windows 2000 Server.
Specify The Dfs Root Share	A shared folder to host the Dfs root. You can choose an existing shared folder or create a new share.
Name The Dfs Root	Provide a descriptive name for the Dfs root.

To create a second root, right-click the domain, and then click New Root Replica Member. The only options for creating a second root are Specify Server To Host Dfs and Select Share For Dfs Root Volume.

In a network environment, it can be difficult for users to keep track of the physical locations of shared resources. When you use Dfs, the network and file system structures become transparent to users. This enables you to centralize and optimize access to resources based on a single tree structure.

After you create a Dfs root, you can create Dfs child nodes. To create a Dfs child node, in the Distributed File System console, click the Dfs root to which you will attach a child node. On the Action menu, click New Dfs Link. In the Create A New Dfs link dialog box, configure the options described in Table 8.3.

Table 8.3 Creating a New Dfs Child Node

Option	Description
Link Name	The name that users will see when they connect to Dfs.
Send The User To This Shared Folder	The Universal Naming Convention (UNC) name for the actual Path of the shared folder to which the child node refers.
Comment	Additional information (optional) to help keep track of the shared folder (for example, the actual name of the shared folder).
Clients Cache This Referral For X Seconds	Length of time for which clients cache a referral to a Dfs child node. After the referral time expires, a client queries the Dfs server about the location of the child node, even if the client has previously established a connection with the child node.

The child node will appear below the Dfs root volume in the Distributed File System console.

In this optional practice, you will share some existing folders, create and share some folders, create a new Dfs root, and then create some Dfs child nodes.

In this exercise, you will create and share some folders.

1. Log on as Administrator.
2. Start Windows Explorer and create and share the folders listed in the following table using all default permissions.

Folder	Share name
C:\Apps\Database	DB
C:\Apps\Wordprocessing	Word
C:\MoreApps\Maintenance	Maint
C:\MoreApps\CustomerService	Custom

3. Close Windows Explorer.

In this exercise, you create and configure a distributed file system (Dfs) on your computer.

1. Click the Start button, point to Programs, point to Administrative Tools, and then click Distributed File System.

The Distributed File System window appears.

2. On the Action menu, point to New, and then click Dfs Root.

The New Dfs Root wizard appears.

3. Click Next.

The wizard displays the Select The Dfs Root Type page.

Notice that there are two types of Dfs roots you can create:

• A domain Dfs root that uses Active Directory directory services to store the Dfs configuration and supports automatic file replication and DNS naming.
• A stand-alone Dfs root that does not use Active Directory directory services and does not support automatic file replication.

4. Click Create A Standalone Dfs Root, and then click Next.

The wizard displays the Specify The Host Server For The Dfs Root page. You will create a Dfs root on your own server.

5. In the Server Name box, confirm that the name of your server is displayed, and then click Next.

The wizard displays the Specify Dfs Root Share page. Notice that you can use an existing share for the Dfs root or the wizard can create a new shared folder for you.

6. Select the Create A New Share option.
7. Type C:\Apps in the Path To Share box, type Shared Apps in the Share Name box, and then click Next.

A Name The Dfs Root page appears allowing you to type in a comment.

8. Type Shared Applications for Marketing in the Comments box, and click Next.

The wizard displays the Completing The New Dfs Root Wizard page, which contains a summary of the choices that you made. An example is shown in Figure 8.3.



Figure 8.3 A summary of choices for the new Dfs root

9. Confirm that the options that the wizard displays are correct, and then click Finish.
10. Leave the Distributed File System window open.

1. In the Distributed File System window's console tree, click \\Server1\ SharedApps (where Server1 is the UNC name of your domain controller).
2. On the Action menu, click New Dfs Link.

The Create A New Dfs Link dialog box appears.

3. Type Word Processing in the Link Name box.
4. In the Send The User To This Shared Folder box, type \\Server1\Word (where Server1 is the UNC name of your domain controller).
5. Click OK.
6. Repeat steps 1-5 to add a child node called Customer Service, which points to the shared folder \\Server1\Custom (where Server1 is the UNC name of your domain controller).

The following table summarizes the nodes being created in this procedure and the next procedure.

Child node	Shared folder	Folder name
Word Processing	\\Server1\Word	C:\Apps\Wordprocessing
Customer Service	\\Server1\Custom	C:\MoreApps\CustomerService
Maintenance	\\second_computer\Maint	C:\MoreApps\Maintenance
Database	\\second_computer\DB	C:\Apps\Database

1. In the console tree, click \\Server1\SharedApps (where Server1 is the UNC of your domain controller).
2. On the Action menu, click New Dfs Link.

The Create A New Dfs Link dialog box appears.

3. Type Maintenance in the Link Name box.
4. In the Send The User To This Shared Folder box, type \\second_computer\Maint (where second_computer is the UNC name of your non-domain controller computer), and then click OK.
5. Repeat steps 1-4 to add a child node called Database, which points to the shared folder \\second_computer\DB (where second_computer is the UNC name of your non-domain controller computer).
6. Close the Distributed File System window.

1. On the domain controller's desktop, double-click My Network Places, double-click the Computers Near Me icon, and then double-click second_computer.

The second_computer window appears, displaying the shared resources on your second computer.

2. Double-click Shared Apps.

The Shared Apps on second_computer window appears, displaying the child nodes of the Shared Apps Dfs.

3. Create a text file in the Word Processing child node, and name the text file WP1.
4. Create a text file in the Maintenance child node, and name the text file Maint1.
5. Close all open windows.
6. Open \\second_computer\Word.

Notice that the file you created on your second computer's Dfs appears in a shared folder on your second computer's shared folder.

7. Close all open windows and log off.

The Microsoft distributed file system (Dfs) for Windows 2000 Server provides users with convenient access to shared folders that are distributed throughout a network. A Dfs share uses a tree structure containing a root and child nodes. The child nodes of the Dfs root represent shared folders that can be physically located on different file servers.

In a network environment, it might be difficult for users to keep track of the physical locations of shared resources. When you use Dfs, the network and file system structures become transparent to users. A user who navigates a Dfs–managed shared folder does not need to know the name of the server on which the folder is shared.

After connecting to a Dfs root, users can browse and gain access to all resources below the root, regardless of the location of the server on which the resource is located. If a server fails, you can move a child node from one server to another without users being aware of the change. All that is required to move a child node is to modify the Dfs folder to refer to the new server location of the shared folders. Users continue to use the same Dfs path for the child node.