Hi, We have a setup including two real servers each of which runs an instance of MySql with the max_connections option set to 1000. In this setup we have run some performance tests with mysqlslap two determine the throughput of the setup. These tests involve simulating many simultaneous users querying the database. Under these conditions we have encountered some problems with the load balancer. Specifically, using ipvsadm -L -n to monitor the connections during the performance test there are intitially many connections represented as inactive. After a few seconds the inactive connections are represented as active in the respective real server. This causes a problem when the Least-Connection Scheduling algorithm is used because the connections are not equally between the two real hosts. The two real hosts are almost equal in terms of processing capacities.
In the following the output of ipvsadm -L -n is shown which probably explains the problem better. ipvsadm -L -n a few seconds in the test simulating 200 MySql clients connecting simultaneously. IP Virtual Server version 1.2.1 (size=4096) Prot LocalAddress:Port Scheduler Flags -> RemoteAddress:Port Forward Weight ActiveConn InActConn TCP 10.0.1.5:3306 lc -> 10.0.1.2:3306 Route 1 71 0 -> 10.0.1.4:3306 Route 1 70 60 ipvsadm -L -n after 30 seconds in the test simulating 200 MySql clients connecting simultaneously. Note that the load balancer uses the Least-Connection scheduling algorithm. IP Virtual Server version 1.2.1 (size=4096) Prot LocalAddress:Port Scheduler Flags -> RemoteAddress:Port Forward Weight ActiveConn InActConn TCP 10.0.1.5:3306 lc -> 10.0.1.2:3306 Route 1 71 0 -> 10.0.1.4:3306 Route 1 130 0 The problem does not occur if the connections are made sequentially and if the number of total connections is below about 100. Is there anything we can do to avoid these problems? Best regards _______________________________________________ Please read the documentation before posting - it's available at: http://www.linuxvirtualserver.org/ LinuxVirtualServer.org mailing list - [email protected] Send requests to [email protected] or go to http://lists.graemef.net/mailman/listinfo/lvs-users
