sticky session not always sticky (1 reply)

Hi list,

we have a backend configuration that uses sticky session based on a
cookie. This works wel in 99.99% of all requests. The problem is with the
0.01% of requests where the client switches backend. Is there any way i
can debug this ? The backend server is not reported to be DOWN. I can't
seem to find any reason why a session would switch backend. It's not like
all sessions on that backend move server.

backend weblogic-forms
mode http
balance roundrobin
cookie SERVERID insert indirect nocache
option httpclose
option forwardfor
option httpchk HEAD /check.txt HTTP/1.0
option log-health-checks
server ias03 10.64.0.81:8888 cookie ias03 check inter 3000 rise 5
fall 6 weight 40
server ias04 10.64.0.82:8888 cookie ias04 check inter 3000 rise 5
fall 6 weight 10
server ias05 10.64.0.181:8888 cookie ias05 check inter 3000 rise 5
fall 6 weight 40
server ias06 10.64.0.182:8888 cookie ias06 check inter 3000 rise 5
fall 6 weight 10

the haproxy version we are using is :

/usr/sbin/haproxy -v
HA-Proxy version 1.5.11 2015/01/31
Copyright 2000-2015 Willy Tarreau <w@1wt.eu>

thank you
Yves