Hey there!

I am looking into using multiple servers for an upcoming project. How do big sites manage to do this? I want 2 SQL servers incase one goes down and to spread server loads. But whats the most efficient way to do this? The databases must synchronise, if one goes down its not useable untill it has been synchronised with the other. Is oracle the way to go? Or can I use MySQL? What about hosting PHP files on multiple servers? What do I have to look out for?

Cheers in advance!