[Pacemaker] Ordering Constraint: Difference Between Stop and Migrate?

[Sven Arnold]

Dear all,

Is it possible with ordering constraints to distinguish stopping a 
resource from migrating it to another node?

I think it is not possible since the resource manager would need to know 
the "migration downtime" in advance but anyways I will give it a try:

Given two resources A and B consider the following cases:

1) A and B are stopped

When A is started, B is not affected
When B is started, A has to be started before

2) A and B are started

When A is stopped, B has to be stopped before
When B is stopped, A is not affected

But:
When A is migrating to another node (and thus stopped temporarily), B 
shall keep running.

The most appropriate rule would be:

order A_before_B 0: A B

but it would not help enforcing stopping B when shutting down A for more 
than a short period.


The use case I have in mind is having a shared storage (DRBD, iSCSI 
Target) with configured failover on two nodes and an iSCSI Initiator and 
other services on other nodes. I would like to keep the dependent 
services running during a planned migration of the storage. And I would 
like to have a "correct" order configured when shutting down services.

Best regards,

Sven