In my experience, sticky sessions open a whole new can of worms. With proxies and VLAN, it's very easy to have an extremely unbalanced load if you use naive IP-based balancing. If one of the servers becomes a "hot spot", adding more servers won't immediately remove the load from that. And when a server dies, the sessions in that server are lost. These problems can be mitigated with an in-memory distributed database overlaid on top of your cluster, but that opens its own can of worms...
Apache and nginx both have an array of good LB algos. I've never seen IP-based LB or hot-spots really. Most app servers support session replication/backup to other node(s). This is really standard stuff in JBoss for instance (my world). Problems that have been solved for years and used at massive scale.
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In my experience, sticky sessions open a whole new can of worms. With proxies and VLAN, it's very easy to have an extremely unbalanced load if you use naive IP-based balancing. If one of the servers becomes a "hot spot", adding more servers won't immediately remove the load from that. And when a server dies, the sessions in that server are lost. These problems can be mitigated with an in-memory distributed database overlaid on top of your cluster, but that opens its own can of worms...
Apache and nginx both have an array of good LB algos. I've never seen IP-based LB or hot-spots really. Most app servers support session replication/backup to other node(s). This is really standard stuff in JBoss for instance (my world). Problems that have been solved for years and used at massive scale.