On our quest to setup a stable MySQL system, we’ve got some tips that we want to share with our fellow developers.
First you need to be clear about your requirement. Load balancing and fault tolerant setup are two different things.
Also note that MySQL replication is different to clustering.

For Load balancing you will want to distribute MySQL access to two or more servers.

For fault tolerant architecture you will need two or more servers but not necessarily using both servers at the same time to balance load.

Master Slave

Master Master

Clustering
- MySQL 5.0 – memory only
- MySQL 5.1 – not stable

Other options:
memcachedb