[ClusterLabs] Antw: How Pacemaker reacts to fast changes of the same parameter in configuration

[Ulrich Windl]

>>> Kostiantyn Ponomarenko <konstantin.ponomarenko at gmail.com> schrieb am 08.11.2016
um 11:40 in Nachricht
<CAEnTH0fJMM6D9W9+0efo6ha3MQ0FuKsTLXt1c7QjswhP9Ctc6Q at mail.gmail.com>:
> Hi,
> 
> I need a way to do a manual fail-back on demand.
> To be clear, I don't want it to be ON/OFF; I want it to be more like "one
> shot".
> So far I found that the most reasonable way to do it - is to set "resource
> stickiness" to a different value, and then set it back to what it was.
> To do that I created a simple script with two lines:
> 
>     crm configure rsc_defaults resource-stickiness=50
>     crm configure rsc_defaults resource-stickiness=150
> 
> There are no timeouts before setting the original value back.
> If I call this script, I get what I want - Pacemaker moves resources to
> their preferred locations, and "resource stickiness" is set back to its
> original value.
> 
> Despite it works, I still have few concerns about this approach.
> Will I get the same behavior under a big load with delays on systems in
> cluster (which is truly possible and a normal case in my environment)?
> How Pacemaker treats fast change of this parameter?
> I am worried that if "resource stickiness" is set back to its original
> value to fast, then no fail-back will happen. Is it possible, or I
> shouldn't worry about it?

What I do interactively is to wait for an "crmd[30170]:   notice: do_state_transition: State transition S_TRANSITION_ENGINE -> S_IDLE [ input=I_TE_SUCCESS cause=C_FSA_INTERNAL origin=notify_crmd ]" message before issuing the next command. I don't know whether there is a scriptable "wait for idle".

> 
> Thank you,
> Kostia