Windows 7 / Networking

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Managing and Troubleshooting DFS

DFS can be managed through the DFS Management console included in the Windows Server 2008 R2 Administrative Tools program group and in the Server Manager console. DFS can also be managed in a command-line environment using the DFS command-line utilities. These utilities include the following:

• DfsUtil: Can be used to manage DFS namespaces, servers, and clients. DfsUtil can also be used to export DFS namespaces to XML files so they can be migrated to new systems.
• DfsCmd: Can be used to manage the folders and targets within an existing DFS namespace.
• DfsrAdmin: Can be used to perform actions on existing DFS Replication groups, including adding new replication group folders and generating reports on existing replicated folder members.
• DfsrDiag: Can be used to force replication, stop replication, or report on replication health.

Using the DFS management console, DFS standalone and domain-based roots can be shown and managed in a single DFS console window. The administrator can check DFS root and folder targets for availability by checking the Connection status of all targets for a particular replication group. Using the DFS Management console, a DFS administrator can also create a DFS Replication Diagnostic report. To create a diagnostic report for replication, perform the following steps:

1. Open the DFS Management console and expand it.
2. Double-click on Replication to reveal the desired replication group. If the desired replication group is not shown, right-click the Replication node, select Add Replication Groups to Display, and follow the steps to add the desired group.
3. Right-click the desired replication group, and select Create Diagnostic Report.
4. When the Diagnostic Report Wizard window opens, select either the health report, propagation test, or propagation report, and click Next.
5. If a report was selected, the report will be saved to the c:\DFSReports folder with a default name; if necessary, change the report name and location and click Next.
6. On the Members to Include page, add or remove the desired folder target servers for the report, and click Next.
7. On the Options page, select the desired options for the report details, to count or not count backlogged files and whether or not to count the replicated files and folders, including data set size on each member, and click Next.
8. Review the selections and if everything looks correct, click Create to generate and display the report.
9. The report will be displayed in the default browser; close the browser and DFS Management console when you are finished.

Taking a Target Offline for Maintenance

When a target needs to be rebooted or just taken offline for a short maintenance window, the connected users must be gracefully referred to another replica, or they must be disconnected from the DFS server.

To take a folder target offline for maintenance, follow these steps:

1. Open the DFS Management console and locate the namespace and expand it to reveal the desired folder and select the folder.
2. Once the folder is selected in the tree pane, in the tasks pane, select the Folder Targets tab and select the target that will be taken offline.
3. Right-click the appropriate target, and select Enable or Disable Folder Target. This option changes the current referral status of a target.
4. Repeat the preceding steps for any additional DFS root or folder targets on the server on which you are disabling referrals.
5. Wait long enough for all the existing connections to close. Usually, after you make the referral change, all users should be disconnected after the cache interval has been exceeded. Start counting after the referral is disabled. One way to know for sure that all users have been disconnected from a target is to open Share and Storage Management on the target server and use the Manage Sessions and Manage Open Files links in the Actions pane to determine if any users and systems are connected.
6. When all connections are closed on the target server, perform the necessary tasks and enable the target from the DFS Management console when maintenance is completed and server functionality has been restored.

Disabling Replication for Extended Downtime

When a server containing a replicated folder target will be offline for an extended period of time, for upgrades or due to unexpected network downtime, removing that server's targets from all replication groups is recommended. Doing this relieves the available replica servers from having to build and store change orders and staging files for this offline server. Because the staging folder has a capacity limit, an offline server might cause the active server's staging folders to reach their limit, essentially shutting down all replication.

When the server is once again available, the administrator can add this server back to the list of targets and configure replication. The data will be moved to the preexisting folder where it can be compared with file IDs sent over on the change orders from the initial master. If the file ID is the same, it will be pulled from the preexisting folder instead of across the WAN to reduce network traffic.

Limiting Connections to Site DFS Targets

In previous versions of DFS, prior to Windows Server 2003 R2 and Windows Server 2008, one issue administrators faced was that users could connect to a folder target across a WAN link for an extended period of time, after only a short network disruption. To enhance performance and keep this situation down to a minimum, DFS administrators can set referral priority and restrict folder target access to local Active Directory site DFS folder target servers. To set referral priority or restrict access to local site target servers, perform the following steps:

1. Open the DFS Management console, and add the necessary namespace to the console.
2. Expand the namespace to reveal the desired folder, right-click the DFS folder, and select Properties.
3. Select the Referrals tab, and check the Exclude Targets Outside of the client's site and click OK.