A server went down, but HAProxy kept it in UP state

A server went down, but HAProxy 1.6.3 kept it in UP state even if check was set and LastChk was L6OK.
The only abnormal thing was check duration still = 0 for hours.
While I reloaded haproxy service it started to fluctuate from 0 to 30 ms.
Anybody saw such behaviour before?

How do you know the server was down but kept UP?

you might want to upgrade to latest code in 1.6 branch (1.6.13) and retry
your test.

Baptiste

I’ve got detailed monitoring. Upgrading seems good idea, but the problem appeared after some month of regular traffic, so it could be difficult to replicate.
Thanks.

Witold Grzebinski

To answer your question from the first post: No, we did not see such a behavior.

Anything more specific would require that you actually provide some details about this. Like your full configuration, and exactly what kind of down you had on the backend server.