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

[Michael Fischer]

On Sat, Jan 16, 2010 at 10:44 AM, Poul-Henning Kamp <phk at phk.freebsd.dk>wrote:

> In message <d002c4031001160929p1f688fc9mcc927dda2c684b86 at mail.gmail.com>,
> Micha
> el Fischer writes:
>
> >For instance sizes larger than 2, I think a consistent hash is needed.
> > Otherwise, the overall hit ratio will fall dramatically upon failure of
> an
> >instance as the requests are rerouted.
>
> If you have perfect 1/3 splitting between 3 varnishes, having one die
> will do bad things to your hitrate until the remaining two distribute
> the load between them.
>
> That's a matter of math, and has nothing to do with the hash algorithm.


Let me put it this way and leave the math up to you:  it will be way worse
if you don't use a consistent hash.

--Michael
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://www.varnish-cache.org/lists/pipermail/varnish-misc/attachments/20100116/36ba6617/attachment-0001.html>