WLBS Does Not Detect Program or Service Problems

ID: Q234151

The information in this article applies to:

Microsoft Windows NT Server, Enterprise Edition version 4.0
Windows NT Load Balancing Service 1.0

SUMMARY

Windows NT Load Balancing Service (WLBS) does not provide failover at the service, program, or port level because WLBS is a TCP/IP load balancer and is not designed to detect when a program or service is not working correctly.

MORE INFORMATION

For example, if Microsoft Internet Information Server (IIS) does not work on a cluster node and WLBS is still running on the node, port 80 or Web packets continue to be routed to the WLBS node. You may receive program error messages on the host because the program is not running there, but the service does not failover to the other hosts because of WLBS design limitations.

When a program does not work, the cause is usually more complex than the service not responding on a port. WLBS relies on external monitoring tools for decision-making processes and remote control if a host needs to be removed from the cluster.

Some independent monitoring tools can control cluster membership based on the availability of content. You can use these tools to monitor programs and services and send a command to stop WLBS on the node with the unsuccessful program or service. The program or service is removed from the WLBS cluster and does not receive any further traffic until it rejoins the cluster.

Examples of Monitoring Tools

Httpmon.exe: You can use Httpmon.exe on a Web server to monitor the status of the Web service. Httpmon.exe is included in the Microsoft Internet Information Server Resource Kit, or you can download it from the following Microsoft Web site:
ftp://ftp.microsoft.com/bussys/utilities/httpmon

Exception Monitor: For additional information about this tool (including its download location), please see the following article in the Microsoft Knowledge Base:
Q160360 Troubleshooting Exceptions in Internet Server Products

Third-Party Monitoring Tools

SiteScope by Freshwater Software (http://www.freshtech.com)

AppManager by NetIQ (http://www.netiq.com)

WhatsUp Gold by Ipswitch (http://www.ipswitch.com)

The third-party contact information included in this article is provided to help you find the technical support you need. This contact information is subject to change without notice. Microsoft in no way guarantees the accuracy of this third-party contact information.

For additional information, please see the following article in the Microsoft Knowledge Base:

Q233178 Third-Party Monitoring Programs Monitor Applications and Ports

Additional query words: application service port httpmon


Keywords          : 
Version           : winnt:1.0,4.0
Platform          : winnt 
Issue type        : kbinfo

Last Reviewed: August 8, 1999