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I'm looking at a setup of an existing application. This application makes use of Amazon's elastic load balancer and then it goes through varnish. Within varnish, we are making use of the round robin load this redundant?

An example of my setup

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We're using the director as round-robin.

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up vote 2 down vote accepted

It makes sense to use multiple Varnish-instances if you have high-volume traffic so that one instance is not enough. If you don't have this high-volume, dual Varnish and dual ELB would be for redundancy only.

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Isn't having the ELB redundant since Varnish may choose a different back end to send the request to? It only becomes useful if ELB is unavailable and if that is the case varnish won't receive any requests anyway. Is my line of thought correct? – Abs Oct 25 '12 at 9:20
Depends on your setup. Varnish is the backend for ELB, and Drupal is the backend for Varnish. You can probably setup balancing strategies on ELB and on Varnish that works together. – pkhamre Oct 25 '12 at 10:00

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