Amazon EC2 + Nginx + Passenger

I have a typical rails application with 200 active users which deployed in Amazon AWS.

My current configurations it is one micro instance with Haproxy and two small instances with nginx and passenger.

How can I choose the type of instances and passenger options for scalable configuration. I ask for examples of valuable combinations of parameters that will be able to support about 1000 active users.

• Type of instance (small, large, ...)


• passenger_max_pool_size value


• what else...