Lesson 5: Configuring Dfs to Gain Access to Network Resources - MCSE Training Kit, Microsoft Windows 2000 Active Directory Services [Electronic resources] نسخه متنی

Lesson 5: Configuring Dfs to Gain Access to Network Resources

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 single Dfs
shared folder serves as an access point to other shared folders in the network. This lesson
introduces you to Dfs.

After this lesson, you will be able to

Configure Dfs for Windows 2000 Server to provide user access to shared folders

Estimated lesson time: 40 minutes

Understanding Dfs

The Microsoft Dfs for Windows 2000 Server allows system administrators to make it easy for
users to access and manage files that are physically distributed across a network. With Dfs,
you can make files distributed across multiple servers appear to users as if they reside in
one place on the network.

Dfs organizes shared folders that can reside on different computers, as shown in Figure
10.12. Dfs provides users with easy navigation to these shared folders. Users do not need to
know where a resource is on a network to gain access to it. Dfs facilitates administering
multiple shared folders.

Figure 10.12 Overview of Dfs

To share file resources across the network, Dfs does the following:

Organizes resources in a hierarchy. Dfs uses a hierarchy of server shares called
a Dfs share. To create a Dfs share, you must first create a Dfs root. A Dfs root
is a container for files and Dfs links. Each Dfs root can have multiple links beneath it, each
of which points to a shared folder. The links of the Dfs root represent shared folders that can
be physically located on different file servers. Table 10.9 describes the two types of Dfs
roots.

Table 10.9 Types of Dfs Roots

Facilitates network navigation. 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. This
simplifies network access because users no longer need to locate the network server on
which a specific resource is located. 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.

Facilitates network administration. Dfs also simplifies network administration.
If a server fails, you can move a link from one server to another without users being aware
of the change. All that is required to move a link 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
link.

Preserves network permissions. A user can gain access to a shared folder through
Dfs as long as the user has the required permission to gain access to the shared folder. If
further restrictions are necessary, NTFS permissions can be set.

NOTE
Only client computers with Dfs client software can gain access to Dfs resources. Computers
running Windows NT 4.0 and later or Windows 98 include a Dfs client. You must download and
install a Dfs client for Windows 95.

Reasons for Using Dfs

You should consider implementing Dfs if

Users who access shared folders are distributed across a site or sites

Most users require access to multiple shared folders

Server load balancing could be improved by redistributing shared folders

Users require uninterrupted access to shared folders

Your organization has Web sites for either internal or external use

Dfs Topology

A Dfs topology consists of a Dfs root, one or more Dfs links, and one or more Dfs shared
folders (also known as replicas), to which each Dfs link points.

For domain-based Dfs, the domain server on which a Dfs root resides is known as a host
server. You can replicate a Dfs root by creating roots on other servers in the domain. This
provides file availability if the host server becomes unavailable.

To users, a Dfs topology provides a unified and transparent access to the network resources
they need. To system administrators, a Dfs topology is a single DNS namespace. With domain-based
Dfs, the DNS names for the Dfs roots resolve to the host servers for the Dfs root.

Because the host server for a domain-based Dfs is a member server within a domain, the Dfs
topology is automatically published to Active Directory by default, thus providing
synchronization of Dfs topologies across host servers. This in turn provides fault tolerance for
the Dfs root and supports optional replication of Dfs shared folders.

Creating a Dfs

The tasks for creating a Dfs are:

Create a Dfs root.

Create a Dfs link.

Add Dfs shared folders (optional).

Set replication policy.

Creating a Dfs Root

You can create a Dfs root on Windows 2000 FAT or NTFS partitions. However, the FAT file
system does not offer the security advantages of NTFS. When setting up a Dfs root, you have
the option of establishing either a domain or a standalone Dfs root.

To create a Dfs root

Click Start, point to Programs, point to Administrative Tools, then click Distributed
File System.

In the Action menu, click New Dfs Root to start the New Dfs Root Wizard. Table 10.10
describes the wizard options that you can configure.

Table 10.10 Options on the New Dfs Root Wizard

Creating a Dfs Link

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. This enables you to centralize and optimize access to resources based on
a single tree structure. Users can browse the links under a Dfs root without knowing where the
referenced resources are physically located.

After you create a Dfs root, you can create Dfs links. Currently, the maximum number of Dfs
links that you can assign to a Dfs root is 1000.

To create a Dfs link

Click Start, point to Programs, point to Administrative Tools, then click Distributed
File System.

Click the Dfs root to which you will attach a Dfs link. In the Action menu, click New
Dfs Link.

In the Create A New Dfs Link dialog box (see Figure 10.13), in the Link Name box, type
a name that users will see when they connect to Dfs.

Figure 10.13 Create A New Dfs Link dialog box

In the Send The User To This Shared Folder box type or browse for the UNC name for the
actual location of the shared folder to which the link refers.

In the Comment box, type optional additional information to help keep track of the shared
folder (for example, the actual name of the shared folder).

In the Clients Cache This Referral For X Seconds box, enter the length of time for
which clients cache a referral to a Dfs link. After the referral time expires, a client queries
the Dfs server about the location of the link, even if the client has previously established a
connection with the link.

Click OK.

The link appears below the Dfs root volume in the Distributed File System console.

Adding a Dfs Shared Folder

For each Dfs link, you can create a set of Dfs shared folders to which the Dfs link points.
Within a set of Dfs shared folders, you add the first folder to the set when you create the Dfs
link, using the Distributed File System console. Subsequent folders are added using the console's
Add A New Replica dialog box. The maximum number of Dfs shared folders allowed in a set of shared
folders is 32.

When you add Dfs shared folders, you can choose which folders will participate in replication.
If you set folders to participate in replication, you must then set the replication policy for the
shared folders, described later in this lesson.

To add a Dfs shared folder

Click Start, point to Programs, point to Administrative Tools, then click Distributed File
System.

In the Dfs console tree, right-click the Dfs link to which you want to assign a shared
folder, then click New Replica.

In the Add A New Replica dialog box (see Figure 10.14), enter or browse for the name of the
new shared folder in the Send The User To This Shared Folder box.

Figure 10.14 Add A New Replica dialog box

In the Replication Policy box

Click Manual Replication to prevent the files located in the folder from participating in
replication.

Click Automatic Replication to cause the files located in the folder to participate in replication. Automatic replication is not available for standalone
distributed file systems and can only be used for files stored on NTFS volumes on Windows 2000
servers.

Click OK.

Setting Replication Policy

You can ensure that the content of folders is always available to users by replicating that
content to other roots or Dfs shared folders in the domain. You can replicate both Dfs roots and
Dfs shared folders. Replication copies the content of one Dfs root to another, or from one Dfs
shared folder to another Dfs shared folder.

Replicating a Dfs Root

Replicating a Dfs root to another server in the domain ensures that if the host server becomes
unavailable for any reason, the Dfs associated with that Dfs root is still available to domain
users.

To replicate a Dfs root

Click Start, point to Programs, point to Administrative Tools, then click Distributed File
System.

In the Dfs console tree, right-click the existing Dfs root that you want to replicate and
select New Root Replica.

The New Dfs Root Wizard guides you through the process of replicating the Dfs root.

Setting Replication Policy for Dfs Shared Folders

When replicating a Dfs shared folder, Dfs stores a duplicate copy of the contents of the
original shared folder in another shared folder.

Replicating a Dfs shared folder is a two-step process. First, you add the Dfs shared folder to a
Dfs link, specifying that the folder will participate in replication. Then, you set the replication
policy for the set of Dfs shared folders associated with that link. Replication of Dfs shared
folders can be done either manually or automatically, as described in the following sections. Do
not mix automatic and manual replication within a set of Dfs shared folders. Using one method of
replication exclusively ensures that the contents of the Dfs shared folders remain
synchronized.

Automatic Replication

For domain Dfs roots only, you can enable Dfs to automatically replicate the contents of a Dfs
shared folder to other folders in the set of Dfs shared folders. This keeps the content of the Dfs
shared folders synchronized as changes to one or more of the Dfs shared folders occurs. Automatic
replication is not available for standalone Dfs and can only be used for files stored on NTFS
volumes on Windows 2000 servers. Other types of files, such as FAT files, must be replicated
manually.

Although invisible to users and administrators, Dfs uses the File Replication Service (FRS)
to perform this function. Within a set of Dfs folders, FRS manages updates across any folders that
are targeted for replication. By default, FRS synchronizes the contents of the Dfs shared folders
at 15-minute intervals.

When you set replication policy, you select one of your Dfs shared folders as the initial
master, which then replicates its contents to the other Dfs shared folders in the set of Dfs shared
folders.

Manual Replication

For domain Dfs, if you do not enable FRS management of Dfs shared folders, you must maintain the
same content in all of the Dfs shared folders manually.

To set replication policy for shared folders

Click Start, point to Programs, point to Administrative Tools, then click Distributed File
System.

In the Dfs console tree, right-click the Dfs link containing the shared folders for which
you want to set a replication policy and select Replication Policy.

In the Replication Policy dialog box (see Figure 10.15), click a Dfs shared folder that you
want to use as the master folder for replication, then click Set Master.

Figure 10.15 Replication Policy dialog box

Click each shared folder in the list and click Enable, then click OK.

NOTE
Do not mix automatic and manual replication within a set of Dfs shared folders. Using one method of
replication exclusively ensures that the contents of the Dfs shared folders remain synchronized.

Practice: Using Dfs

In this practice you share some existing folders, and create and share some new folders. Then
you create a new Dfs root and create some Dfs links.

IMPORTANT
To complete the optional procedures in this practice, you must have two computers running Windows
2000 Server. This practice also assumes that one of the two computers is configured as a domain
controller and the other computer is configured as a member server in the domain. If you have only
one computer, read through the steps in the procedures marked as optional to learn how to perform
them in the future.

To share existing folders

Log on to your domain at your domain controller as Administrator.

Start Windows Explorer and share the folders listed in Table 10.12, using all default
permissions. You created these folders in Exercise 7 of Lesson 4, earlier in this chapter.

Table 10.12 Shared Folders for Practice

To create new shared folders on a remote computer (optional)

In Windows Explorer, create the folders listed in Table 10.13 (where C:\ is the name of your
system drive) on your second (remote) computer and share them, using all default permissions.

Table 10.13 New Shared Folders for Practice

To create a new Dfs root

On your domain controller, click Start, point to Programs, point to Administrative Tools,
then click Distributed File System.

The Distributed File System console opens.

On the Action menu, click New Dfs Root.

Windows starts the New Dfs Root Wizard.

Click Next.

The wizard displays the Select The Dfs Root Type page. In this exercise
you will create a domain Dfs root.

Click Create A Domain Dfs Root, then click Next.

The wizard displays the Select The Host Domain For The Dfs Root page.

In the Domain Name box, confirm that microsoft.com (or the name of your domain) is
displayed, 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.

In the Server Name box, confirm that SERVER1 (or the name of your server) is displayed, then
click Next.

The wizard displays the Specify The 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.

In this exercise you will let the wizard create a new shared folder for you.
You have to provide both the location of the folder on your computer and a share name.

Select the Create A New Share option. Type c:\app-dfs in the Path To Share box (where
C:\ is the name of your system drive), then type Shared Apps in the Share Name box.

Click Next.

The Distributed File System message box appears, asking if you want to
create the C:\App-Dfs folder.

Click Yes.

The wizard displays the Name The Dfs Root page. The wizard fills in the Dfs Root Name box for
you.

Click Next.

The wizard displays the Completing The New Dfs Root Wizard page, which contains a summary of the
choices that you made.

Confirm that the options that the wizard displays are correct, then click Finish.

Notice that the \\microsoft.com\Shared Apps Dfs root now appears in the
console tree (where microsoft.com is the name of your domain).

In the following two procedures you will create Dfs links according to
Table 10.14 (where C:\ is the name of your system drive).

Table 10.14 Dfs Links for Practice

To add Dfs links on your domain controller

Open the Distributed File System console and in the console tree, click
\\microsoft.com\Shared Apps (where microsoft.com is the name of your domain).

On the Action menu, click New Dfs Link.

The Distributed File System console displays the Create A New Dfs Link
dialog box.

Type Database in the Link Name box.

In the Send The User To This Shared Folder box, type \\server1\DB (where Server1 is
the name of your domain controller).

Click OK.

Repeat Steps 1 to 5 to add another link called Word Processing, which points to the shared
folder \\Server1\Word (where Server1 is the name of your domain controller).

To add a Dfs link to a remote computer

In the console tree, click \\microsoft.com\Shared Apps (where microsoft.com is the name of
your domain).

On the Action menu, click New Dfs Link.

The Distributed File System console displays the Create A New Dfs Link dialog box.

Type Maintenance in the Link Name box.

In the Send The User To This Shared Folder box, type \\second_computer\maint
(where second_computer is the name of your non-domain-controller computer), then click OK.

Repeat Steps 1 to 4 to add another link called Customer Service, which points to the shared
folder \\second_computer\Custom (where second_computer is the name of your
non-domain-controller computer).

Close the Distributed File System console.

To gain access to a Dfs root

On your domain controller or your second computer, double-click My Network Places,
double-click Entire Network, click the Entire Contents link, double click Microsoft Windows Network, and then double-click Microsoft (where Microsoft is the name of your domain).

Double-click SERVER1.

Windows Explorer displays a list of all shared folders on your domain
controller. Notice that one of the shared folders is Shared Apps, your Dfs root.

Does Windows 2000 provide an indication that Shared Apps is a Dfs root and not an ordinary
shared folder?

To view the Dfs links, double-click Shared Apps.

Windows Explorer displays the Shared Apps On Server1 window, which shows all the links of Shared
Apps.

Does Windows 2000 indicate that the folders inside Shared Apps are Dfs links and not ordinary
folders?

Close all open windows.

Answers

Lesson Summary

In this lesson you learned that 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 links. The links of the Dfs root
represent shared folders that can be physically located on different file servers.

It might be difficult for users to keep track of the physical locations of shared
resources in a network environment. 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, or the actual file name.

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 link from one server to another without users being aware of the change. All that is
required to move a link is a modification of the Dfs folder to refer to the new server location of
the shared folders. Users continue to use the same Dfs path for the link.

In the practice portion of this lesson you shared some existing folders, created some new
share folders, created a Dfs root, and then created some Dfs links.