how to use replication to forward transactions

Normal replication goes from host A to host B. But using the mysql my.cnf directive log_slave_updates you can store and forward transactions from an intermediary log to another host. So in this example, B is a slave of A; B specifies log_slave_updates, and then C as a slave of B gets all transactions from both A and B. Not quite multi-master support.

I have used this when cutting over a new system where existing hosts X & Y are replicating and I want to add a new host that will set up a new pair A & B.

Hope this is useful.