Each server inserts a "hearbeat" value into a replicated table. The
server can see when the last heartbeat it received from its master
was. If a heartbeat has not been received from the master in 3
minutes, and the master is available, then the replication status is
checked with "show slave statu
I have four machines A,B,C,D..
A and B are "dual masters" while C and D are read only slaves
A <---> B
| |
C D
I have a load balancer that connects all clients to A, and when it
fails, connects them to be. In practice it is a little more
complicated, because if a server becom
