Hi All,

 

We use pacemaker as cluster engine under the hood and manage it by getting
CIB, change and then put. I can do a lot of changes at once.

 

The question is about internal action scheduler. As I found, the logic of
applying new config sounds like:

1.      Validate, analyze new config, build target resource layout with
respect to config, location constraints and current state
2.      Build action list for resource state change with respect to order
constraints
3.      Schedule actions into queue 
4.      Render actions from queue

 

The question is: if I put two config change very fast, one by one and second
arrive before every scheduled action finished, will every scheduled action
from the first config complete? Mean, all the actions coming from second
config to be queued after all scheduled on the first push.

 

The background of the question: I use "constraint chains", means order like
start A => B =>C stop C=>B=>A and it is essential to keep the order.
However, If A, B and C running and I push config where all of them deleted,
pacemaker has no constraints in the new config and schedule A,B,C stop as
independent action, and this leads to resource failures. I already asked in
the group and answered that this is behavior by design, Paacemaker only use
the new config for change planning, so A,B and C become unconstrained
orphans. My workaround was to send intermediate config, keeping resource to
delete in config, but set target state "stopped'. For now, I am sending the
intermediate config and request status until every resource to delete is
stopped. However, if the scheduler put new actions after already planned, I
need no wait and request status, I only need send cib with target state
stopped and then immediately send cib with deleted resource. As the stop
sequence already in the scheduler queue, it should work correctly and faster
then my first approach.

 

Thank you in advance for every advice and suggestion!

 

Sincerely,

 

Alex

 

 

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