Hi Sheeri,I know this is a long comment, but if you could find the time to reply, I would be very gafuertl.I’m working with a few friends to try to launch a social network type of site, with many of the typical social network site features (profiles, photos, comments, videos, etc). We are using LAMP environment. I’ve been tasked with researching MySQL Cluster, MySQL Replication, and how various other large sites cope with large amounts of traffic and how they solve their scalability and HA issues. We don’t want to become popular one night and be overwhelmed by the traffic.What I’ve found is this:- Replication is widely used by many of the largest sites- memcached is widely used by many of the largest sites- MySQL Cluster is not widely used at all (not sure why seems like a great product)As far as I can tell, Replication has some problems:- the delay in syncing current data to the slaves.- replication is ideal for read-intensive applications.- need to modify web application to read from slaves and write to master.- MOST IMPORTANTLY: the single point of failure and bottleneck point with 1 master server.From what I read and understand, MySQL Cluster is ideal for both read and write intensive applications and is built for high availability and scalability. Seems like a great solution. But why is no one using it for web applications?It seems everyone is recommending replication, but I have concerns about it:1. Initially, I expect that there will be as many writes as reads as more and more users create profiles, post photos, comments, etc. Considering that replication is great for read-intensive applications, would replication be of any help here?2. The SPOF with 1 Master MySQL server really scares me. I’ve read about Master-Master Replication but again, the bottleneck would be the writes. Am I wrong?3. Even if I partition my data across different master databases, if one of them fails then part of the site (and potentially the entire site) might go offline. Or am I wrong?4. How do these big sites use replication without running into write performance issues?Thanks for any help and suggestions!Konstantin