WLBS Does Not Detect Program or Service Problems
ID: Q234151
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The information in this article applies to:
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Microsoft Windows NT Server, Enterprise Edition version 4.0
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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
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