Activating Load Balancing

To enable the load balancing, the following entry must be set in configuration file ./etc/loadbalance.xml. See section Failover concept .

<Set name="enableLoadbalance">true</Set>

Configuration File ./etc/startup.xml

As already described, the Node Controller distributes jobs. The distribution can be based on one of two methods: The round-robin or the load factor method. The round-robin alternately delegates tasks to the existing Working Nodes. The load factor method, on the other hand, uses the workload (which internally is calculated by the data volume, the tasks at hand, and the available worker threads) of the single Working Nodes to determine the node to use. If no Working Node can be determined, the Node Controller itself (e.g. because there is no node so far) takes the task.

Use false if you want to use the round-robin method and true for the load factor method in the following entry.

<Call name="useLoadInformation"><Arg type="boolean">false</Arg></Call>

Optional

(a) If you use two DMZ servers or have a second Node Controller in a cold standby system, set the entry

<Set name="informDMZOfNewPeer">True</Set>

to true to notify the DMZ server to reference to the newly started Node Controller. In that case, all the pending transmissions will be delegated to the new Node Controller.

(b) If the directory ./conf is not mounted, all changes in ./conf and ./etc/admin/datawizard can be forwarded to the active Working Nodes by the Node Controller by setting entry

<Set name="replicateFiles">True</Set>

to true. Alternatively, setting

<Set name="replicateAdminFiles">True</Set>

only replicates the files in ./etc/admin/datawizard.

Note: See also function replicate file().

(c) Enter all nodes of the Load Balancing system in configuration file ./etc/admin/dazawizard/lb_nodes.properties (the format is always factory-id=IP-or-hostname:Port-MessageService). This file only has to be maintained on the Node Controller. If there is a valid configuration file, all the active Working Nodes configured in this file will be notified that the started Node Controller is now the 'active' one and all the active Working Nodes will reference to the started Node Controller from that moment on.

(d) If the performance factor method is used and the hardware of the Working Nodes varies, the entry

<Set name="performanceFactor">1.3</Set>

can be used to compensate performance differences. The value has to be > 1 and will be used to multiply the load factor with. Example: Let's assume we have one working node with powerful hardware and another working node with less powerful hardware and the same load factor was calculated for both working nodes (without considering the performance factor). Now we give the working node with the less powerful hardware a performance factor of 1.3 and we multiply it with its load factor, i.e. it now has a higher load factor and new load would therefore be distributed to the working node with the more powerful hardware.

This completes the configuration of the node controller(s).