Replication
One of Windows NT’s networking features is the ability to automatically duplicate a specific set of folders between Windows NT computers across the network. This feature is known as replication, and it has many potential uses for network administrators. However, the most common use of replication by far is the synchronization of user logon scripts (automated batch files that users automatically execute when they log on) between multiple Windows NT servers on a network. In fact, this usage is so common that Microsoft made the default location of user logon scripts in Windows NT Server a subdirectory of the default directory used for replication (%SYSTEMROOT%\System32\Repl\ Import\Scripts). However, synchronization is not the only use for replication on a Windows NT network. You can also use replication for duplicating other kinds of data, such as reference databases or other types of information that need to be synchronized between network computers.
Tip: When you set up replication, you should choose data that is primarily read-only (not written to by network users) and not choose large files that are changed frequently. The frequent replication of large files may put undue stress on network resources and significantly slow the overall speed of the network.
Windows NT 4.0’s replication feature requires two participants: export servers and import computers. Windows NT Servers can be either type (or both simultaneously); Windows NT Workstations can only be import computers. For replication to occur, at least one machine must be configured as an export server and one as an import computer.
To set up your Windows NT computer as a replication import computer, choose the Replication button, which opens the Directory Replication dialog box (shown in Figure 5.54).
By default, the Do Not Import option button at the top of the dialog box is selected, meaning that this computer does not participate in directory replication. To have your Windows NT Workstation participate in directory replication, follow these steps:
Set up your Windows NT Server export server computer(s) with at least one directory configured for replication (as described in the Microsoft Windows NT Server documentation).
Use User Manager to create a user account (or select an existing user account) and add the account to the Replicator local group. This account will be used in Step 3 as the logon account name for the Windows NT Service that handles the replication process.
For More Information: For more information about the User Manager application, see “Managing Users and Groups with User Manager,” Chapter 8.
Configure the Directory Replicator Service in the Control Panel’s Services applet. For best results, set the startup type of the service to automatic (to autostart when Windows NT boots) and configure the service to use a logon account that is a member of the Replicator local group (which you configured in Step 2).
For More Information: For more information about configuring Windows NT Services, see the description of the Services applet.
On the Windows NT Workstation that acts as an import computer, run the Control Panel’s Server applet and choose Replication. In the Directory Replication dialog box, click the Import Directories control button. This automatically deselects the Do Not Import button.
At this point, the To Path box will be automatically filled in with the
Windows NT default import directory name,
%SYSTEMROOT%\System\Repl\Import,
where %SYSTEMROOT% is the drive and folder of your Windows NT base directory (e.g., c:\Winnt). If you wish to use another directory, enter that folder name in the To Path box.
Choose one or more export servers (usually Windows NT Server computers) from which you will import data. To do so, click the Add button, which displays the Choose Domain dialog box.
In the Choose Domain dialog box, double-click the name of the domain (or type in the domain name in the Domain box) containing the export computer you wish to select. When the list of available computers in the domain is displayed, select the export server computer of your choice by double-clicking the machine’s name or clicking the machine’s name and choosing OK.
Repeat Step 7 for each additional export server computer from which you wish to import replication data (you can choose more than one). Use the Remove button if you wish to remove any of the computers you have previously selected from the list of export servers.
To manage your replicated directories, you can click the Manage button. The button displays the Manage Imported Directories dialog box (shown in Figure 5.55), which lets you add or remove subdirectories from the display window. By doing so you gain additional control of particular subdirectories (of your main replication import directory) that are imported to your Windows NT system. To add a subdirectory, click the Add button and enter the subdirectory name. The subdirectory is then added to the list of subdirectories. Once the subdirectory is added, you can view statistics about it in the main window of the dialog box.
Special Note: It is not necessary to manually add subdirectories to the list; subdirectories that are imported from export computers are listed automatically. Adding them ahead of time simply lets you gain control over how they are imported.
The statistics available include whether or not the directory is locked (i.e., cannot be updated), how many locks exist, when the directory was first locked (if it is locked), when the last replication update occurred on a file in the directory, and the replication status. The Status column may contain any of the indicators presented in Table 5.8.
Use the Remove button to remove subdirectories from the list, although this is usually an unnecessary step. Using the Remove button does not remove the subdirectory itself, but only the the listing. The subdirectory will re-appear if it is still being imported from an export server.
To prevent a particular subdirectory from being imported to your Windows NT computer, add that subdirectory to the list (if it does not already appear) and click the Add Lock button. The total number of locks for that directory is then incremented by one. To remove a lock from a directory, which decrements the number of locks by one, click the Remove Lock button.
Caution: Directory replication will only occur if the number of locks on a subdirectory is zero.
Alerts
The Alerts button of the Server applet lets you configure where administrative alerts related to this Windows NT computer are sent. Administrative alerts are warnings that are issued automatically by the system when any of a predefined set of events occurs on your Windows NT computer. Warnings are issued about many events, including security and access problems, user session problems, power loss to the system (when the UPS service is configured), and printer-related problems.
Choosing the Alerts button brings up the Alerts dialog box, which is shown in Figure 5.56.
To control where administrative alerts are sent, simply type the name of the computer or user to which you want the alert sent in the New Computer or Username box and click the Add button. This moves the computer/username into the Send Administrative Alerts To box at right. To remove a computer or user from the alert recipients windows, highlight the computer or username and click the Remove button.
For administrative alerts to function properly, certain conditions must be met on the sending and receiving computers. For alerts to be sent, the Alerter and Messenger services must be running on the computer issuing the issuing the alert. For alerts to be received on a Windows NT computer, that computer must be running the Messenger service. For Windows for Workgroups or Windows 95 computers to receive alerts, the WinPopup application should be running.
Tip: To ensure that administrative alerts will be sent or received properly on a Windows NT computer, be sure that the startup types of the appropriate services have been started and configured in the Control Panel’s Services applet with a startup type of Automatic. To be able to send alerts, the Alerter and Messenger services must be running on the Windows NT computer; receiving alerts requires only the Messenger service.
Tip for Windows Workgroups Users: To automatically enable the WinPopup application, which lets a Windows for Workgroups computer receive administrative alerts, choose the Network applet of the Windows for Workgroups Control Panel and select the check box labeled Enable WinPopup.
Tip for Windows 95 Users: To automatically run the WinPopup application when Windows 95 starts so that administrative alerts will be received, place a shortcut to the WinPopup application in the Windows 95 computer’s Startup folder.
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