I have a quad core xeon, 8GB ram, and only 2 x 1TB SATA drives right now. I am trying to figure out how to scale my application to handle as much load and traffic per day as possible. I have an industry network site and it's currently bogging around 30,000 signup's in a day, 60k UV, and 600-1,000,000 pageviews per day. It was going so slow I had to shut the server off, and now I am losing money and traffic.
I'm pretty certain part of it is the PHP code and MySQL queries (hired them from India). What can I do to optimize and make sure the server is handling as much traffic as possible without bottlenecking. As I am expecting even more signups every day. It's a very database intensive site as it's a "networking" site for a certain niche, and you must be logged in, so everything revolves around MySQL.
PS. CentOS 5 64bit, PHP5, MySQL5. I know the database is MyISAM, and I am pretty sure they didn't index the tables too well either.
Thanks for the advice!