4 Steps to solve the Split-Brain
Manually choose a node which data modifications will be discarded. We call it the split brain victim.
Choose wisely, all modifications will be lost! When in doubt run a backup of the victim's data before you continue.
When running a Pacemaker cluster, you can enable maintenance mode. If the split brain victim is in Primary role, bring down all applications using this resource.
Now switch the victim to Secondary role:
victim# drbdadm secondary resource
victim# drbdadm disconnect resource
victim# drbdadm -- --discard-my-data connect resource
for DRBD 8.4.x:
victim# drbdadm connect --discard-my-data resource
Resync will start automatically if the survivor was in WFConnection network state.
If the split brain survivor is still in Standalone connection state, reconnect it:
survivor# drbdadm conn
