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This article describes a software update that enables you to configure two additional dependent logical unit server (DLUS) systems for Internet Protocol - Data Link Control (IP-DLC) host systems connections in Microsoft Host Integration Server 2010.

When you configure a host systems connection that uses the Systems Network Architecture (SNA) IP-DLC link service in SNA Manager, you can specify a primary and a backup DLUS system to provide fault tolerance for dependent logical units (LUs) such as logical units for 3270 emulation, logical units for applications (LUA), and dependent LU 6.2. The primary and backup DLUS entries are configured on the Address tab of the host systems connection that you want to configure.

In some environments, you may have to specify more than two DLUS systems for additional fault tolerance. However, the SNA IP-DLC link service currently supports no more than two DLUS systems.

Cumulative update information

This update is included in cumulative update package 8 for Host Integration Server 2010. For more information about how to obtain the cumulative update package, see Cumulative update package 8 for Host Integration Server 2010.

More Information

After you apply this update, the SNA IP-DLC link service can be configured to support two additional DLUS systems to provide for no more than four DLUS systems for additional fault tolerance for host systems connections and dependent LUs.

Important Follow the steps in this section carefully. Serious problems might occur if you modify the registry incorrectly. Before you modify it, back up the registry for restoration in case problems occur.

To configure the additional DLUS systems, follow these steps:

  1. Click Start, click Run, type regedit, and then click OK.

  2. Locate the following subkey in the registry:

    Note Replace the "x" in "SNAIPx" with the number that matches the IP-DLC link service that you want to change. For example, if you have one IP-DLC link service installed on your Host Integration Server 2010 system, you should replace "x" with 1.

  3. Right-click ExtraParameters, point to New, and then click String Value.

  4. Type PrimaryDLUS, and then press Enter.

  5. Double-click PrimaryDLUS, and enter the name of the additional DLUS system by using the format Network_Name.Control_Point_Name (for example, MSFT.SYS3).

  6. Click OK.

  7. Right-click ExtraParameters, point to New, and then click String Value.

  8. Type BackupDLUS, and then press Enter.

  9. Double-click BackupDLUS, and enter the name of the additional DLUS system by using the format Network_Name.Control_Point_Name (for example, MSFT.SYS4).

  10. Click OK.

  11. Exit Registry Editor.

  12. Restart the SNA IP-DLC link service so that the change takes effect. The easiest way to do this is to restart the SNA Server service or the SnaBase service. When you restart either service, users who are connected to the Host Integration server are disconnected.

The PrimaryDLUS and BackupDLUS systems that are specified in the registry entries are used as the third and fourth backup DLUS systems in case the two DLUS entries that are configured in the Host systems connection properties dialog box are unavailable.

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