Gateway Load Balancer (GWLB) determines the availability of real servers through health checks. If exceptions are detected in health checks, you can use the following methods for troubleshooting.
Note:
If an exception is detected in health checks, GWLB will stop forwarding traffic to the exceptional real server.
If exceptions are detected on all the real servers in health checks, requests will be forwarded to all the real servers.
Highly Frequent Health Checks
When GWLB is configured in the console to send a health check packet every 5 seconds, the real server actually receives one or more health check requests per second. This higher frequency of health checks is mainly related to the implementation mechanism of GWLB health checks for real servers.
Assume that 1 million client requests are distributed to 4 GWLB servers and then forwarded to real servers. Each GWLB server performs health checks separately. Therefore, if the GWLB instance is configured to send a health check request every 5 seconds, each GWLB server will send a health check request every 5 seconds. In this case, the real server may receive 4 health check requests within 5 seconds.
This implementation mechanism is efficient and accurate, avoiding false removal of servers.
If your business is load-sensitive, highly frequent health checks may affect normal business access. You can reduce the business impact by setting a larger time interval (such as 15 seconds) for health checks.
If a real server is added to multiple target groups and bound to multiple GWLB instances, each GWLB instance sends health check packets to detect the health status of the server, resulting in a higher frequency of health checks.