Replicating on two or more MySQL master database servers

1. MySQL Master-Master Replication Fails With ERROR 1200 (HY000) on Master

2. Password problem are solved by carefully checking your grant statements

3. When you have more than two master servers, you must use log-slave-updates option to ensure that changes are propagated in a chain. Beware of infinite looping of updates. Infinite loop is prevented with:
replicate-same-server-id = 0

4. When in trouble delete the master.info file and restart the server. It may contain stale information which overrides your configuration in my.cnf.

5. Always keep a tail -f of MySQL server log file to spot any replication problems during testing phase

6. Setup scripts to notify you when replication fails.