I'm planning to host a website where in the first phase I would target 30,000 users. It is in php and runs on Apache server. I'm assuming 8,000 users can be online in worst case scenario and 1000 of them will be uploading photographs.

A photograph will be resized to around 1MB at client side and one HTTP request is uploading only one photograph.

My plan:

• 2 Small EC2 instances to run Apache httpd
• 2 Small EC2 instances to DB (Postgresql). I to write data and other its read replica.
• EBS volumes for DBs
• Last, Amazon S3 for uploaded photographs.

My question here

• Is Small EC2 instance more than what I require. I mean should I go for micro
• Is 8000 simultaneous user a right no. (to decide what EC2 instance to choose) for a new website
• Or should I go for Small instance so to make it capable of spikes