On a master-slave replication I have some shared tables which are written by master only.
In addition to the shared data, I have some "log tables" which are only relevant for the single machine, not to be shared and not to be backed-up.
If there is no mistake in the application on the server, it will not directly write into the slave machine - except the un-shared log tables. Isn't it possible to set the readonly flag for the shared tables explicitely? I found some similar questions, but no trustworthy solution yet :-(
whole slave readonly as conf setting: http://dev.mysql.com/doc/refman/5.1/en/replication-options-slave.html#option_mysqld_read-only