[lvs-users] setting weight to 0 (no persistence!), but still new connections

Tim.Einmahl at kba.de Tim.Einmahl at kba.de
Thu Apr 25 11:47:06 BST 2013


Hi all,

we have been using lvs in production with redhat rhel5 with direct routing successfully for years now.
Maintenance of server was no problem, because setting the weight to 0 avoided new connections and we only had to wait 
for the current tcp-sessions to end on the maintained server.

But with our new rhel6-cluster we are having most of the time the problem that still new http-connections
are being directed to the server that has a weight of 0, although we don't use persistent connections and there is no
keepalive enabled in httpd.conf, so each tcp-connection ends after very short time.


config:

IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn
TCP  192.168.0.1:http wlc
  -> lxweb1-stage:http     Local   1      0          0
  -> lxweb2-stage:http     Route   1      0          0



Running stress test with ab from another server:
ab -n 600000  -c 30 http://192.168.0.1/


IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn
TCP  192.168.0.1:http wlc
  -> lxweb1-stage:http     Local   1      12         14323
  -> lxweb2-stage:http     Route   1      10         13868


setting weight to 0:

IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn
TCP  192.168.0.1:http wlc
  -> lxweb1-stage:http     Local   0      7          14317
  -> lxweb2-stage:http     Route   1      13         13888


a few minutes minutes later:

IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn
TCP  192.168.0.1:http wlc
  -> lxweb1-stage:http     Local   0      12         14304
  -> lxweb2-stage:http     Route   1      8          13902



Running ipvsadm -Lnc | grep -v FIN_WAIT shows, that there are only a few established connections
and some SYN_RECV. Repeating this command after a few seconds also makes clear, that there are no ports
being reused from the ESTABLISHED-connections. So I have no idea why there are still active connections on the 
server with weight 0.


Any hint is appreciated
Thanks very much for your effort

Best regards
Tim









More information about the lvs-users mailing list