You should be able to delete (undeploy) from all nodes in a cluster with each node running, that's what farming is for...
Just delete a war from any node in the cluster, the others should soon follow. Then drop the new .war in after that, and then too, the others should follow.
Hope it helps.
Well i have been doing that way only. Deleting the war from the farm folder and dropping the new war. But that would still make the app unavilable for sometime ( atleast a few mins ). The application owners want the app to be available 24/7. They do not want any distruption as they are users connected from all over the world. This is what concerns me ..how can we deploy the app without disrupting ?
Farming doesn't support any kind of rolling redeploy. If you want a rolling redeploy you need to deploy to each server's deploy folder manually or use a script to do it.