users@glassfish.java.net

Achieving Load balancing + HA on two servers

From: <glassfish_at_javadesktop.org>
Date: Wed, 17 Sep 2008 04:49:48 PDT

Hey Folks

I am kinda new to glassfish. In one of our requirements we need to set up loadbalancing and achieve HA using two servers. SO here is what I did :

On HOST2
Created node agent 'node2' with reference of HOST1 (Also Acting as DAS)

On HOST1 (Also acting as DAS)
Created domain -> Created node-agent 'node1' -> Created Cluster 'cluster1' -> created two instance in the cluster, one of each node, node1 and node2 -> deployed application on cluster -> Started the cluster

After doing this I was able to access the sample application at following url
http://host1:38080/clusterjsp
http://host2:38080/clusterjsp

Then on HOST1 i deployed lbpluigin and made changes in obj.conf and magnus.conf as required -> ran asadmin commands to create lb config, enabled cluster on lb, enabled applications -> exported conf to loadbalancer.xml ->copied loadbalancer.xml to webserver instance's conf directory. -> deployed the conf through WADM deploy config -> restared server instances through DAS.->restarted webserver

After doing this I was able to access the sample application at following url
http://host1/clusterjsp
(virtual server's listener IP is 80)

Then I conducted following tests :

I checked the access log of both host1 and host2 and verified that the requests are being distributed. Test Passed

Stopped the instance on host 2 and checked that lb reroutes the traffic to instance at host1 : Test Passed

Stopped the instance on host 1 and checked that lb reroutes the traffic to instance at host2 : Test Passed

I unplugged the network cable of HOST2 and hit the url http://host1/clusterjsp. Traffic redirected to HOST1.Test passed

NOW : THE COMPLICATION OCCURS.
I unplugged the network cable of HOST1 and the url http://host1/clusterjsp returns 404 not found . TEST FAILED
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[b]AND HERE IS THE QUESTION :What if HOST1 goes down completely, say because of power failiure. The url http://host1/clusterjsp will not return anything as the LB which was configured on HOST1 itself has stopped running.[/b]

What could be the workaround to achieve 100% HA on a setup involving two servers ?

Any kind of quick help will be highly appreciated.
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Thanks
anzy
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