Round-Robin Director Backends

Corey Hammerton CoreyH at
Mon Oct 3 16:24:30 CEST 2011

Are there any plans to make the Varnish directors be able to read the backend response WITHOUT having to put it into VCL code?

For instance, a client requests an asset (a picture) that is present on one server and not on any of the others, if the response from the current backend server is a 404 automatically go to the next backend configured in the director.

From: Per Buer [mailto:perbu at]
Sent: Monday, October 03, 2011 4:25 AM
To: Corey Hammerton
Cc: varnish-misc at; Gordon Cook
Subject: Re: Round-Robin Director Backends


On Thu, Sep 29, 2011 at 8:52 PM, Corey Hammerton <CoreyH at<mailto:CoreyH at>> wrote:


I have an environment with multiple backend servers that require most images (static content) be replicated out to all servers, this is causing unnecessary load on our backend servers. To mitigate this problem we plan to put in a Varnish system to grab the assets from the backend servers and send them to the client VIA a round-robin director.

If Varnish cannot find the asset on the current backend server does it automatically go to the next backend in the list? If not what VCL code do we need to insert to accomplish this?

You should probably have a look at saint mode. It can do what you want.

Per Buer, CEO
Phone: +47 21 98 92 61 / Mobile: +47 958 39 117 / Skype: per.buer
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