when issuing pcs cluster stop --all the stop sequence will:

stop all services on node1 -> stop cluster on node1
stop all services on node2 -> stop cluster on node2
....

There are 2 major problems with approach:

1) at somepoint there will be loss of quorum that can potentially block some resources that need quorum to stop (so when you get to the N node the resource will fail to stop and node will kill itself)

2) some applications (for example galera) have their own internal quorum and needs to be stopped all together to avoid corner case data corruption. Generally we can assume (for now at least) that external application quorum follows our quorum rules.

What we see in OpenStack is that stop --all on 3 node, will result in:

- moving tons of services around unnecessarily (since they will all die sooner or later)
- node fencing when stopping the last node because services can´t write to the db anymore (lack of internal quorum)

My recommendation here is:

on pcs cluster stop --all -> stop all resources -> stop cluster (at this point it´s irrelevant if it´s done one at a time or all together)

on pcs cluster stop -> this operation should verify if removing a node from the cluster will cause loss of quorum and abort. Of course we want to allow a manual override --pretty-please-i-know-i-will-lose-quorum-go-on