[ClusterLabs] Antw: [EXT] Trying to understand dampening (ping)

[Klaus Wenninger]

afair the idea of dampening isn't to configure the behavior of the cluster
- like be robust against some kind of glitches.
It is rather there to keep resources used to write content to the CIB under
control.

Klaus

On Thu, Oct 14, 2021 at 8:29 AM Ulrich Windl <
Ulrich.Windl at rz.uni-regensburg.de> wrote:

> Hi!
>
> IMHO "dampening" was a very bad term, and it had confused me right from the
> start.
> Maybe "change_ignore_time" would have been better.
> But actually a true moving average (over a fixed window) would be much
> preferrable.
> Maybe exponential averaging, too.
>
> And the description in pingd is very poor, also:
> dampen (integer, [1s]): Dampening interval
>     The time to wait (dampening) further changes occur
>
> Regards,
> Ulrich
>
> >>> martin doc <db1280 at hotmail.com> schrieb am 13.10.2021 um 17:01 in
> Nachricht
> <
> PS2P216MB0546168E8F60EE9D89131EFCC2B79 at PS2P216MB0546.KORP216.PROD.OUTLOOK.COM
> >:
>
> > In the ping resource script, there's support for "dampen" in the use of
> > attrd_updater.
> >
> > My expectation is that it will cause "ping", "no‑ping", "ping" to result
> in
>
> > the service being continually presented as up rather than to flap about.
> >
> > In testing I can't demonstrate this, even using attrd_updater directly.
> >
> > To test out how attrd_updater works, I wrote a small script to do this:
> >
> > attrd_updater ‑n my_ping ‑D
> > attrd_updater ‑n my_ping ‑p ‑B 1000 ‑d 3s
> > sleep 1
> > for i in 0 1 2 3 4 5 6 7 8 9; do
> > attrd_updater ‑n my_ping ‑Q
> > sleep 1
> > attrd_updater ‑n my_ping ‑p ‑U 0 ‑d 3s
> > done
> >
> > The output always has the first line as 1000 and every other line with a
> > valud of "0" ‑ as if there was no dampening actually happening.
> >
> > Even if I modify the above to do ‑U 1000, ‑U 0, ‑U 1000, doing ‑Q at any
> point
> > always shows the last value supplied, with no evidence of any smoothng
> as a
>
> > result of dampening.
> >
> > Is the problem here that the ‑Q doesn't retrieve the value for my_ping
> using
>
> > the same method as is used for resource scripts?
> >
> > Am I totally misunderstanding how dampening works?
> >
> > Thanks.
>
>
>
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