nginx- polling, weight, ip_hash, fair mode

 There under linux Nginx, LVS, Haproxy services and so can provide load balancing services, and Nginx provides several distribution (strategy):

　　1, the polling (default)
　　each request individually assigned to a different time order back-end server, if the back-end server is down, can be automatically removed.

　　2, weight representation, a default weight, the higher the weight customers allocated more ends, as follows;

　　upstream server_pool{   

　　　　      server 127.0.0.1:8081 weight=2;

　　　　     server 127.0.0.1:8082 weight=1;    

                }

　　3, ip_hash
　　each request assigned by hash result Access ip so that each visitor to access a fixed back-end server, can solve the problem of session. E.g:

       upstream server_pool{    ip_hash;     server 127.0.0.1:8081;     server 127.0.0.1:8082;     }
 　　

　　4, fair (third party) by the response time of the allocation request to the backend server, the response time is short preferentially allocated

　　upstream server_pool{    server 127.0.0.1:8081;;     server 127.0.0.1:8082;     fair;     }