I have 2 MySQL servers, Master & Slave , running on Ubuntu 12.04. I have replication working from the Master to the Slave. If the Master goes down and the Slave is used, how do I get data to replicate back to the Master once it's up ?
You may want to read:
Once you have switched to the slave (i.e., the slave is the new master), you will have to load a backup onto the old master and start replication towards it exactly as you had previously done with the old slave. In other words, you cannot reuse what you already had on the old master before switching.