Usage of the Shard director ( rampup period )

[Yiannis Karayiannidis]

Hello Guys,
thanks a lot for the answer Geof.
The shard director does what is expected to do.
It was a misunderstanding from my side.

Thanks again
and sorry for the noise

Regards



On Thu, Nov 14, 2019 at 8:32 PM Geoff Simmons <geoff at uplex.de> wrote:

> On 11/14/19 11:43, Yiannis Karayiannidis wrote:
> >
> >  sub vcl_init {
> >         new dir_b = directors.shard();
> >                 dir_b .add_backend(wb3);
> >                 dir_b .add_backend(wb2);
> >                 dir_b.add_backend(wb1);
> >                 dir_b .set_rampup(2m);
> >                 dir_b .reconfigure();
> > }
> >
> > I'm trying to debug  rampup period for a failed backend, cause it seems
> to
> > me that the server is getting back in the pool before the 2 minutes
> rampup
> > period.
>
> What exactly do you mean by "getting back in the pool before the 2
> minutes"? What were you expecting?
>
> Rampup means that requests are directed to a backend, gradually and
> increasingly, during the rampup period after a backend is added to the
> pool. Say after the backend goes from failing health probes to being
> healthy again.
>
> Specifically, set_rampup(2m) means that during the two minutes after a
> backend is added to the pool, requests are directed to the alternative
> backend with linear decreasing probability, from 100% just after the
> backend is added, to 0% after the two minutes are up. For example, at 90
> seconds, there is a 75% probability that the backend will receive
> requests that sharding would direct to it.
>
> So it's to be expected that a backend will receive requests during rampup.
>
>
> HTH,
> Geoff
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Yiannis Karayiannidis
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