Avoid 503 during failover to backup?

Hello Willy and list,

We're running haproxy with (roughly) the following config:

listen foo 0.0.0.0:8080

    balance leastconn
    cookie C insert indirect nocache
    option persist
    option redispatch
    option allbackups
    option httpchk HEAD /test HTTP/1.0
    fullconn 200
    server www1 192.168.0.1 weight 1 minconn 3 maxconn 100 cookie A check inter 5000
 server www2 192.168.0.2 weight 1 minconn 3 maxconn 100 cookie B check inter 5000
 server www3 192.168.0.3 weight 1 minconn 3 maxconn 100 cookie C check inter 5000

    server bu1 192.168.0.10 weight 1 minconn 3 maxconn 100 check inter 20000 backup 
When we shut down all www servers (www1-www3) haproxy will shortly after route requests to the backup server - just as intended.

Our problem is that *during* the failover some requests will get a 503 response from haproxy: "No server available to serve your request".

More precisely: When we shut down all www servers and then make a request before the 5 second timeout has elapsed this request will receive the 503 response.

Is there a way to avoid this gap and make the failover completely transparent?

best regards
-jj Received on 2008/12/02 14:59