Strategies for splitting load across varnish instances? And avoiding single-point-of-failure?

Michael Fischer michael at
Sat Jan 16 22:55:07 CET 2010

On Sat, Jan 16, 2010 at 1:37 PM, Poul-Henning Kamp <phk at>wrote:

>Are you saying that the default hash is not a mod-n-type algorithm?
> Well, it is mod-n, with the footnote that n has nothing to do with
> the number of backends, because these have a configurable weight.
> >If not, what happens when the failed backend is restored to service?
> It's probably simplest to paraphrase the code:
>        Calculate hash over full complement of backends.
>        Is the selected backend sick
>                Calculate hash over subset of healthy backends

Ah, ok.  That should behave reasonably in the event of a backend failure if
you're implementing Varnish tiers.  Thanks for the clarification.

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