I need a solution to store images (1 billion) which users will upload to a website via PHP or Javascript upload (website will have 1 billion page views a month using Linux Debian distros) assuming 20 photos per user maximum (10 thumbnails of size 90px by 90px and 10 large, script resized images of having maximum width 500px or maximum height 500px depending on shape of image, meaning square, rectangle, horizontal, vertical etc).

Assume this to be a LEMP-stack (Linux Nginx MySQL PHP) social-media or social-matchmaking type application whose content will be text and images.

Since everyone knows storing tons of images (website users uploaded images in this case) are bad inside a single directory or NFS etc, please explain all the details about the architecture and configuration of the entire setup of storage solution, to store 1 billion images on any method you recommend (no third-party cloud storage like S3 etc. It has to be within the private data center using our own hardware and resources.).

The solution has to include both the storage solution and organizing the images uploaded by users. How will we organize the users images if a single user will not have more than 20 images (10 thumbs and 10 large of having either width or height 500px)? Please consider that this has to be organized in a structural way so we can fetch a single user's images via PHP/Javascript or API programmatically through some type of user's unique identifier(s).