263 lines
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263 lines
22 KiB
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<h1><font size=7>Microsoft Distributed File System for Microsoft
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Windows NT Server 4.0 Administrator's Guide</font></h1>
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<h2><a name="Contents">Contents</a></h2>
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<p><a href="#Practical_Uses">Practical Uses of Dfs Trees</a><br>
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<a href="#How_Dfs_Works">How Dfs Works</a><br>
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<a href="#How_Users_See">How Users See and Connect To Dfs Trees</a> <br>
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<a href="#Administering_Dfs">Administering Dfs Trees</a></p>
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<hr>
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<p>Microsoft® Distributed File System for Microsoft Windows NT® Server (Dfs) enables distributed file system capabilities on Windows NT Server. A distributed
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file system provides a single tree structure for multiple shared volumes located on different servers on a network. A user accessing a volume on a Dfs tree does not
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need to know the name of the server where the volume is actually shared.</p>
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<p>With the Dfs software, you can create a Dfs tree root on any server running the Windows NT Server software released at the PDC. Windows NT Server version
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4.0. </p>
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<p>This document explains what Dfs is, why it is useful, and how to create and administer Dfs trees.</p>
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<hr>
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<h1><a name="Practical_Uses">Practical Uses</a> of Dfs Trees</h1>
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<p>A Dfs tree makes network access easier for users, who no longer have to manually locate which server any particular resource is on. After connecting to the root of
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the Dfs tree, they can then browse for and access all resources contained within the tree, no matter which server on which the resource is physically located.</p>
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<p>With Dfs, if a server goes down and you need to replace it, or you need to move a volume from one server to another, you can do so without informing users of the
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change. Instead, you modify the Dfs tree to refer to the new server location for the resource, and users can continue to use the same Dfs path to access the volume.</p>
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<p>Because you can have multiple Dfs trees on your network, you can create a different Dfs tree for each type of user on your network. For example, an engineering
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firm could create one Dfs tree containing all the volumes needed by their engineers, another for payroll and benefits people, and so on. Any particular volume can be
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included in one or more Dfs trees, ensuring that every user can access all the resources they need. </p>
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<p>With Dfs, you can increase data availability and transparently distribute load across multiple servers. This is because multiple servers can serve as duplicate storage
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points for a single volume.</p>
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<p>Dfs gives you the flexibility to expand your network as smoothly as possible. When you add disk storage to your network, the physical server on which you add it
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can be independent of where in the logical namespace the new storage is made available.</p>
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<p>Dfs also complements Microsoft Internet Information Server. For example, if you set up a World Wide Web site on your network, you could have the root of the
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web site be the root of a Dfs tree. If you later move a resource within the Dfs tree, all HTML links will continue to work. </p>
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<p><a href="#Contents">Return to Contents</a></p>
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<hr>
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<h1><a name="How_Dfs_Works">How Dfs Works</a></h1>
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<p>Dfs organizes your shared-file resources into a tree structure. A shared-file resource that is part of a Dfs tree can be accessed by either its Dfs path name or its
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<em>\\servername\sharename</em> path. </p>
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<p>Each Dfs tree has one or more <em>root</em> <em>volumes</em>. In this release, you can have one level of volumes, called <em>leaf</em> <em>volumes</em>, beneath the root level. Leaf volumes can be
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physically located on different servers than the root volume. (Future releases of Dfs will include support for multiple levels of volumes under a root).</p>
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<p>A Dfs tree that has more than one root volume is called a <em>fault tolerant dfs tree</em>. The contents of the multiple root volumes are identical, and provide multiple points
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of failure for the entire tree. A Dfs tree that is configured to always have only one root volume is called a <em>standalone Dfs tree</em>. </p>
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<p>The root volumes of Dfs trees must be hosted on a server running the PDC release of Windows NT Server. </p>
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<p><a name="Figure_1">Figure 1</a> shows a sample standalone Dfs tree. The Dfs paths to each volume are shown in bold, while the network paths are shown in italics.</p>
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<p><img src="dfs.gif" align=bottom width=595 height=364></p>
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<p><font color="#000000"><strong>Figure 1-- A sample Dfs tree structure</strong></font></p>
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<p><font color="#000000">You can have multiple Dfs trees on your network. Any shared folder can be a volume in multiple Dfs trees.</font></p>
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<p><font color="#000000">The various folders on a particular server can be made volumes on different Dfs trees, but a server can have only one folder that serves as a Dfs root.</font></p>
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<p><font color="#000000">Dfs automatically creates short file and directory names for long names, so that 16-bit applications can use Dfs paths to access files.</font></p>
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<h2><font color="#000000"><font size=5>Nesting and Expanding Dfs Trees</font></font> </h2>
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<p><font color="#000000">Although each particular Dfs tree in this release is limited to two levels of volumes, each volume can contain multiple levels of folders. Additionally, you can create a
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multileveled tree by nesting Dfs trees inside of each other. You do this by adding the root volume of one Dfs tree as a leaf volume in another Dfs. Creating a
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multilevel tree this way is transparent to users; they do not know when they have crossed from one Dfs tree to another.</font></p>
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<p><font color="#000000">You can also add levels to a Dfs tree by using the local storage of the server hosting the root volume. Any files and folders under the Dfs root volume will be visible
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through the Dfs tree. In addition, when you add leaf volumes to a Dfs tree, you can add them under folders at any level under the Dfs volume directory. In the
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sample in </font><a href="#Figure_1"><font color="#000000">Figure 1</font></a><font color="#000000">, <strong>info</strong> is a folder added locally at the server under the folder shared as <strong>dfs</strong>. The <strong>reports</strong> and <strong>releases</strong> volumes are added under the <strong>info</strong> folder.</font></p>
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<h2><font color="#000000"><font size=5>Volumes That Include Alternate Paths</font></font></h2>
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<p><font color="#000000">Note that some volumes on a Dfs tree (such as <strong>\\human_resources\dfs\benefits</strong> in the example in </font><a href="#Figure_1"><font color="#000000">Figure 1</font></a><font color="#000000">) can use one or more shared folders for storage. If a
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volume uses more than one shared folder, it has alternate paths.</font></p>
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<p><font color="#000000">Alternate paths provide load balancing, and allow the volume to be accessed even if one of the volume servers goes down. However, the Dfs software does not
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replicate information between the two servers; network administrators must ensure that the data on the servers stays synchronized through other means.</font></p>
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<p><font color="#000000">Because the Dfs software does not synchronize alternate paths automatically (without third-party replication software), alternate paths are best suited for read-only
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volumes, where users will not be adding files or modifying existing files.</font></p>
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<h2><font color="#000000"><font size=5>Security</font></font></h2>
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<p><font color="#000000">The Dfs software does not add any permissions or security limitations beyond those already assigned to the files or shares themselves. A user can access a volume
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through the Dfs tree as long as the user has permission to access the shared folder directly.</font></p>
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<p><font color="#000000">It is not necessary for a user to have permissions for a root volume in order to access leaf volumes. For example, in the tree in </font><a href="#Figure_1"><font color="#000000">Figure 1</font></a><font color="#000000">, if a user has permissions for
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the share <strong>\\insurance\public</strong> (located in the Dfs as <strong>\\human_resources\dfs\insurance</strong>), then the user can access that share through the Dfs tree, even if the user
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does not have permissions for the <strong>\\human_resources\dfs </strong>share.</font></p>
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<p><font color="#000000">Only administrators can administer a Dfs tree.</font></p>
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<h2>Local File Structure on Servers that Contain Root Volumes </h2>
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<p>When you add a leaf volume to a Dfs tree, a blank folder is automatically created in the root volume directory. This blank folder serves as a junction point to the leaf
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volume.</p>
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<p>Dfs prevents you from deleting any of these folders manually. If you use Dfs Administrator to remove a volume, the junction point folder is automatically removed.</p>
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<p>If you delete the Dfs software from a root server without first removing the leaf volumes from the Dfs tree it hosted, you can then delete the junction point folders
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manually.</p>
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<p><a href="#Contents">Return to Contents</a></p>
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<hr>
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<h1><a name="How_Users_See">How Users See</a> and Connect To Dfs Trees</h1>
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<p>Users view and access resources through a Dfs tree just as they view and access other resources on the network. When browsing a network, a Dfs root appears
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just like a share name of a shared folder. Fault-tolerant Dfs trees appear as \\domain_name\dfsname, while standalone Dfs trees appear as \\servername\dfsname.
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For example, with the sample Dfs tree in <a href="#Figure_1">Figure 1</a>, a user browsing the network would see dfs as a shared directory available under the human_resources server.</p>
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<p>Users can browse through a tree transparently, no matter the location of each volume or the file system used for that volume. Users can make connections to and
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assign local drive letters to the any folder of a Dfs tree. </p>
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<p>When a user views the contents of the root volume through its Dfs name, they see both the Dfs volumes located under that volume, as well as any contents of the
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shared folder that comprises the root volume. For example, in <a href="#Figure_1">Figure 1</a>, when a user views the contents of <strong>\\human_resources\dfs</strong>, they see the <strong>benefits</strong>,
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<strong>insurance</strong>, and <strong>health</strong> Dfs volumes, as well as any files and folders located in the <strong>\\human_resources\dfs</strong> folder.</p>
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<p>Users of computers with the PDC Windows NT software can see and access Dfs trees. </p>
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<p><a href="#Contents">Return to Contents</a></p>
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<hr>
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<h1><a name="Administering_Dfs">Administering Dfs</a> Trees</h1>
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<p>You administer Dfs trees by using the Dfsadmin tool.</p>
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<p>With Dfsadmin, you can add and remove volumes to a Dfs tree, modify volumes, create alternate paths to a volume, and view and configure information about the
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volumes contained in a tree. You can remotely administer any Dfs tree on the network that you have permissions for.</p>
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<h4>To start Dfsadmin</h4>
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<ol>
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<li>On the <strong>Start</strong> menu, click <strong>Programs</strong>, then click <strong>Administrative Tools</strong>, then click <strong>Dfs Administrator</strong>.<br>
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-Or- <br>
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On the <strong>Start</strong>, menu, click <strong>Run</strong>. In the <strong>Open</strong> box, type <strong>dfsadmin</strong>, and then click <strong>OK</strong>. </li>
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</ol>
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<p> If the local server already hosts a Dfs tree, you can begin administering it. Otherwise, you can either create a Dfs tree on the local server, or remotely administer
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another Dfs tree. To remotely administer a Dfs tree, click <strong>No</strong> when prompted whether to host a Dfs, then select the tree to administer.</p>
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<p>If you want to create a Dfs root on the local computer, see the following section, "Creating a New Dfs Tree Root." </p>
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<h2>Creating a New Dfs Tree Root</h2>
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<p>To create a Dfs tree root in this release, you must work physically at the server on which you want to create the root.</p>
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<h4>To create a root volume for a new Dfs tree</h4>
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<ol>
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<li>While working physically at the server which will host the root, start Dfsadmin. (To do so, on the <strong>Start</strong> menu, click <strong>Programs</strong>, then click <strong>Administrative
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Tools</strong>, then click <strong>Dfs Administrator</strong>.)</li>
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<li>Click <strong>Yes</strong> to create a Dfs root (host).</li>
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<li>Click either <strong>Create a new Fault Tolerant Dfs</strong> <strong>in this domain</strong> or <strong>Create a Stand Alone Dfs on this machine</strong>, then click <strong>OK</strong>.</li>
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<li>Under <strong>Host a Dfs on share</strong>, select the shared directory that will serve as the root. Or, to use a new share as the root, click <strong>New</strong> <strong>Share</strong> and specify the
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folder. Then click <strong>OK</strong>.</li>
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<li>Click <strong>Yes</strong> to restart the computer.</li>
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</ol>
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<p>If you click <strong>No</strong> when prompted whether to host a Dfs, you can choose an existing Dfs tree to remotely administer. If, during this time, you then decide to start
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hosting a Dfs tree on the local computer, use the following procedure:</p>
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<h4>To create a root volume for a new Dfs tree after starting Dfsadmin</h4>
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<ol>
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<li>On the <strong>Dfs</strong> menu, click <strong>Configure Dfs</strong>. </li>
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<li>Click either <strong>Create a new Fault Tolerant Dfs</strong> <strong>in this domain</strong> or <strong>Create a Stand Alone Dfs on this machine</strong>, then click <strong>OK</strong>.</li>
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<li>Under <strong>Host a Dfs on share</strong>, select the shared directory that will serve as the root. Or, to use a new share as the root, click <strong>New</strong> <strong>Share</strong> and specify the
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folder. Then click <strong>OK</strong>.</li>
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<li>Click <strong>Yes</strong> to restart the computer.</li>
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</ol>
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<p> </h2>
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<h2>Creating Another Root-Level Participant Volume</h2>
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<p>Fault-tolerant Dfs trees can have multiple servers which all host identical copies of a root volume of a Dfs tree. This provides multiple point of failure for the entire
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tree.</p>
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<p>To configure this, first create the original root volume by following the procedure in "Creating a New Dfs Tree Root" (and be sure to select <strong>Create a new Fault
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Tolerant Dfs</strong> <strong>in this domain</strong>). Then create the other root-level participants by using the following procedure.</p>
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<p><strong>To create another root-level participant</strong></p>
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<ol>
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<li>While working physically at the server which will host the root, start Dfsadmin. </li>
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<li>Click <strong>Yes</strong> to create a Dfs root (host).</li>
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<li>Click <strong>Join an Existing Fault Tolerant Dfs</strong> <strong>in this domain</strong>, then click <strong>OK</strong>.</li>
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<li>Under <strong>Host a Dfs on share</strong>, select the shared directory that will serve as the Dfs volume. Or, to use a new share as the Dfs volume, click <strong>New</strong> <strong>Share</strong> and
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specify the folder. Then click <strong>OK</strong>.</li>
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<li>Click <strong>Yes</strong> to restart the computer.</li>
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</ol>
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<p> </h2>
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<h2>Stop Hosting a Dfs Root Volume</h2>
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<p>Use this procedure to stop hosting a Dfs root on a server.</p>
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<p><strong>To stop hosting a Dfs root volume</strong></p>
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<ol>
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<li>While working physically at the server, start Dfsadmin. </li>
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<li>In the <strong>Dfs </strong>menu, click <strong>Stop Hosting Dfs</strong>.</li>
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</ol>
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<p> </h2>
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<h2>Adding a Leaf Volume to a Dfs Tree</h2>
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<p>Any folder you want to add to a Dfs tree must already be shared.</p>
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<h4>To add a volume to a Dfs tree</h4>
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<ol>
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<li>In the Dfsadmin main window, select the volume under which you want the new volume to appear. </li>
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<li>On the <strong>Dfs</strong> menu, click <strong>Add</strong> <strong>To</strong> <strong>Dfs</strong>. </li>
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<li>Under <strong>When a user references this path</strong>, type the volume name for the new volume as an extension of a current volume in the tree. For example, if you
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are creating the \\human_resources\dfs\insurance volume in <a href="#Figure_1">Figure 1</a>, you would type <strong>insurance</strong> immediately after <strong>\\human_reosources\dfs\</strong>. (To add the
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new volume farther down in the directory tree, type as much of the path as you need; for example, to create the \\human_resources\dfs\info\reports volume,
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you would type <strong>info\reports</strong> after <strong>\\human_resources\dfs\</strong>.) You can use the <strong>Browse</strong> button to browse the current structure of the Dfs tree, and select the
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Dfs path to append your new volume to. </li>
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<li>Under <strong>Send the user to this network path</strong>, type the path of the shared folder to add as a volume. (Or use the <strong>Browse</strong> button to browse the network and
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select the volume.) </li>
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<li>Optionally, type a comment in the <strong>Comment</strong> box. </li>
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<li>Click <strong>OK</strong>. </li>
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</ol>
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<p>  </p>
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<h2>Removing a Leaf Volume from a Dfs Tree</h2>
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<h4>To remove a volume from the Dfs</h4>
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<ol>
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<li>In the Dfsadmin main window, select the volume to remove. </li>
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<li>On the <strong>Dfs</strong> menu, click <strong>Remove From Dfs</strong>. </li>
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<li>Click <strong>Yes</strong>. </li>
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</ol>
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<p>  </p>
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<h2>Adding Alternate Paths for a Volume</h2>
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<p>A volume can use one or more shared folders for its storage. If the volume uses more than one, it has alternate paths.</p>
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<p>When a volume includes alternate paths, user requests to access the volume are distributed among the alternate paths.</p>
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<p>The Dfs software does not ensure that the contents of the alternate paths of a volume are replicated. Network administrators must manually ensure that the
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alternates stay synchronized.</p>
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<h4>To add an alternate path for a volume</h4>
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<ol>
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<li>In the Dfsadmin main window, double-click the volume. </li>
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<li>Click <strong>Add</strong>. </li>
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<li>Click <strong>Yes</strong>. </li>
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<li>Under <strong>Send the user to this network path</strong>, type the path of the shared folder to add as an alternate path for the volume. </li>
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</ol>
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<p>  </p>
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<h2>Removing a Volume's Alternate Path</h2>
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<h4>To remove an alternate path from a volume</h4>
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<ol>
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<li>In the Dfsadmin main window, double-click the volume. </li>
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<li>Under <strong>Send the user to this network path</strong>, select the network path you want to remove. </li>
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<li>Click <strong>Remove</strong>. </li>
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<li>Click <strong>OK</strong>. </li>
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</ol>
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<p>  </p>
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<h2>Saving and Restoring the Dfs Structure Table</h2>
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<p>You can save the current structure of the Dfs tree to a file, which you can later reload to restore the Dfs volume structure. Note that this saves only the links
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between volumes, not any volume contents. The save files are server-specific comma separate files, with a .csv file extension</p>
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<h4>To save the current Dfs tree structure</h4>
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<ol>
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<li>On the <strong>Dfs</strong> menu, click <strong>Save As</strong>. </li>
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<li>Type a name for the file in the <strong>File name</strong> box, and then click <strong>Save</strong>. </li>
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</ol>
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<h4>To restore a previous Dfs tree structure</h4>
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<ol>
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<li>On the <strong>Dfs</strong> menu, click <strong>Load</strong>. </li>
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<li>Select the file to restore, and then click <strong>Open</strong>. </li>
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</ol>
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<p> </p>
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<h2>Filtering the View of Volumes</h2>
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<p>You can filter the list of volumes shown in the Dfsadmin main window. You can filter volumes by name, comment, and the number of alternate servers that provide
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storage for the volume.</p>
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<h4>To filter the list of volumes</h4>
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<ol>
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<li>On the <strong>View</strong> menu, click <strong>Filter</strong>. </li>
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<li>Click the filtering option you want, and then click <strong>OK</strong>. </li>
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</ol>
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<p>For more information on any of the filtering options, right-click the option and then click <strong>What's This?</strong></p>
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<p> </p>
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<h2>Stopping and Starting the Dfs Service</h2>
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<p>Dfs is implemented as a service (the Distributed File Service). </p>
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<p>You can start and stop the service manually by using either <strong>Services</strong> in Control Panel or the command line. The commands are <strong>net stop dfs</strong> and <strong>net start dfs</strong>.</p>
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<p> </p>
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<h2>Administering a DFS Tree From the Command Prompt</h2>
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<p>DFS provides the following commands you can use from the command prompt.</p>
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<dl>
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<dt><strong>dfscmd /map</strong> <em>\\dfsname\dfsshare\path \\server\share\path</em> [<em>comment</em>] </dt>
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<dd><br>
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Adds the shared folder<em> \\server\share\path</em> as a volume in the specified Dfs tree. </dd>
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<dt><strong>dfscmd /unmap</strong> <em>\\dfsname\dfsshare\path</em> </dt>
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<dd><br>
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Removes the volume from the Dfs tree. </dd>
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<dt><strong>dfscmd /add</strong><em> \\dfsname\dfsshare\path \\server\share\path</em> </dt>
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<dd><br>
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Adds<em> \\server\share\path </em>as an alternate path for the specified Dfs volume. </dd>
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<dt><strong>dfscmd /remove</strong> <em>\\dfsname\dfsshare\path \\server\share\path</em> </dt>
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<dd><br>
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Removes the specified alternate path from the specified volume. </dd>
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<dt><strong>dfscmd /view</strong> <em>\\dfsname\dfsshare</em> [<strong>/partial</strong> | <strong>/full</strong>] </dt>
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<dd><br>
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Displays all the volumes in the Dfs tree. Without arguments, only the volume names are displayed. Specifying <strong>/partial </strong>causes comments for each volume to
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also be displayed. Specifying <strong>/full </strong>causes the network path of each volume (including all alternate paths) to be displayed. </dd>
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</dl>
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<p><a href="#Contents">Return to Contents</a></p>
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<p> </p>
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<p><font size=2>Microsoft, Windows, and Windows NT are registered trademarks of Microsoft Corporation in the U.S. and/or other countries. <br>
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</font></p>
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<p><font size=2>Other companies and product names may be trademarks of their respective companies.<br>
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</font> </p>
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<p> </p>
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<p> </p>
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</body>
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</html>
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