Wednesday, October 1, 2014

Why we need atleast 2 WKMs for WSO2 Product cluster

Assume we have an ELB cluster with 2 nodes connected to AS and ESB clusters. (Here the well known members are 2 ELBs) All nodes are connected and working fine (members joined the cluster).
Let’s say, if both ELBs were down and then restarted, the ASs and ESBs also have to be restarted to join the cluster again.


This is a known issue in Hazelcast. If all WK members fail, the entire cluster has to be restarted. Thats why they have recommend to have two WKs members at minimum.


To avoid this situation you can configure the AS and ESB management nodes also as well-known members. Clustering details can found on AS[2] and ESB[3] links.




To configure AS & ESB mgt nodes as WK members, follow the following steps
- Update the AS mgt node axis2.xml file with WK member details as follows (do the same for ESB as well)
<members>
   <member>
       <hostName>xxx.xxx.xxx.
206</hostName> <!-- this should be the ELB details -->
       <port>4500</port>
   </member>
   <member>
       <hostName>(its own ip)</hostName>
       <port>(AS mgt node localmember port)</port>
   </member>
</members>


- Next you have to add the WK member details to the loadbalancer.conf file in ELBS
esb {
      domains{
         wso2.esb.domain {
              tenant_range *;
              group_mgt_port 4500;
              members <ip-of-mgt-node>:<local-port-of-mgt-node>;
              members 192.168.8.126:4010;
              
         mgt {
              hosts mgt.esb480.wso2.com;
         }
         worker {
              hosts wkr.esb480.wso2.com;
         }
     }
  }

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