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Failing health checks - Timeout waiting for data

 

Information

 

Summary:

This article will discuss how to mitigate the Timeout waiting for data log message.

Environment:

Product: LoadMaster

Version: Any

Platform: Any

Application: Any

Question/Problem Description:

Why are health checks failing for my application?

Steps to Reproduce:  
Error Message: Removing RS <RealServerIP>:<RealServerPort> from VS <VirtualServiceIP>:<VirtualServicePort>(<VirtualServiceName>) - Timeout waiting for data
Defect Number:  
Enhancement Number:  
Cause:

This happens when either ICMP Ping checks are used or an L7 protocol is used for health checking.

Resolution:

If ICMP Ping health checks are failing, this indicates a break in network connectivity.

If L7 protocols are failing, this indicates that the LoadMaster is expecting to receive a Status Code back from the server, but that information is never provided.

For a list of what the LoadMaster is expecting back, visit section 2.2 of this article: https://support.kemptechnologies.com/hc/en-us/articles/6515106815373-Health-Checking

Workaround:

If it's been confirmed that a response is received, but timing is not correct to allow for passing health checks, then Rules & Checking > Check Parameters can be increased globally, or this can be done by navigating to Virtual Services > View/Modify Services > modify the desired Virtual Service > if applicable, expand the SubVS tab and modify the desired SubVS > Real Servers.

Timing can be checked by taking a packet capture from the LoadMaster, as outlined here: https://support.kemptechnologies.com/hc/en-us/articles/6370901430157-Troubleshooting-Connectivity-to-the-Virtual-Service

Notes:  

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