fullconn Specify at what backend load the servers will reach their maxconn May be used in sections :

defaults frontend listen backend yes yes no no yes yes yes yes Arguments :

is the number of connections on the backend which will make the servers use the maximal number of connections. When a server has a "maxconn" parameter specified, it means that its number of concurrent connections will never go higher. Additionally, if it has a "minconn" parameter, it indicates a dynamic limit following the backend's load. The server will then always accept at least connections, never more than , and the limit will be on the ramp between both values when the backend has less than concurrent connections. This makes it possible to limit the load on the servers during normal loads, but push it further for important loads without overloading the servers during exceptional loads.

Since it's hard to get this value right, haproxy automatically sets it to 10% of the sum of the maxconns of all frontends that may branch to this backend (based on "use_backend" and "default_backend" rules). That way it's safe to leave it unset. However, "use_backend" involving dynamic names are not counted since there is no way to know if they could match or not. Example :

The servers will accept between 100 and 1000 concurrent connections each

and the maximum of 1000 will be reached when the backend reaches 10000

connections.

backend dynamic fullconn 10000 server srv1 dyn1:80 minconn 100 maxconn 1000 server srv2 dyn2:80 minconn 100 maxconn 1000 See also : "maxconn", "server"