Multi master mysql with automerge data if node disconnected
Galera has the principle that a "quorum" in needed to declare that the cluster is alive.

For example if 'a' disconnects from 'b' and 'c', but 'b' and 'c' are still talking to each other, then


b and c have a quorum (more than half the servers), so they declare they are the cluster.
'a' does not have a quorum, so it refuses to accept any writes.
If the network gets repaired, 'a' will ask b &amp; c for the latest updates and get back in sync.


That is Galera.  If you have plain MySQL multi-master, you have a nightmare when the network breaks.

NDB Cluster works a different way -- every node can be disconnected.  However, you must provide rules for "eventual consistency" of the data.