Here is the quick notes from MySQL Cluster by Stewart Smith session that I attended today in the MySQL conference 2008.
- What it is
    
- Clustering of in memory databases in a shared-nothing system
 - Designed for HA, 99.9% Uptime (not really) and sub-second failover
 - Supports Hot (online) consistent backup along with compression
 - No locks are used during the backup as NDB uses a global counters
 
 - Think as virtual file system
 - Redundancy
    
- NoOfReplicas (1,2,3,4), For production use 1 or 2 but don’t use any other as it may have bugs (2 is preferred and well tested mode)
 - 1 means no redundancy (a node fails and cluster fails)
 - 2 means two copies …