...
https://docs.linbit.com/doc/users-guide-84/s-resolve-split-brain/
stop cluster, on broken node first!
sudo pcs cluster standby jtel-2-5-pn-1
sudo pcs cluster standby jtel-1-5-pn-1
...
sudo pcs cluster unstandby jtel-1-5-pn-1
sudo pcs cluster unstandby jtel-2-5-pn-1
check cluster
sudo pcs resource show
check DRBD
sudo cat /proc/drbd