How NGINX Reverse Proxy handle image/video file upload or download - nginx

Question

First off, I'll explain my situation to you. I'm building a server for storing and retrieve data for my phone application. I'm new to NGINX. What I know point of using load balancing/reverse proxy is to improve performance and reliability by distributing the workload across multiple servers. But i'm not understand while it working with image/video file. Let say below is mine NGINX config file
upstream backend {
server backend1.example.com;
server backend2.example.com;
server backend3.example.com;
}
server {
listen 80;
server_name example.com;
location / {
proxy_pass http://backend;
}
}
I have few question here.
First while i upload an image/video file, did i need to upload image into those all backend server or there is other way?
Second if I just save it to a separate server which only store image, while I requesting and download image or video file I proxy it to that specified server then what is the point of load balancing with image/video file since reverse proxy is to improve performance and reliability by distributing the workload across multiple servers?
Third does amazon s3 really better for storing file? Does it cost cheaper?
I'm looking for solution which can be done it by my own server beside using third parties.
Thx for any help!!

Answer 1

You can either use shared storage e.g. NFS, or upload to both servers, or incorporate a strategy to distribute files between servers, storing each file on a single server.
First two options logically are the same and provide fallover, hence improving reliability.
Third option, as you note, does not improve reliability (may be somehow, if one server fails second may still serve some files). It can improve performance, though, if you have many concurrent requests for different files and distribute them evenly between servers. This is not achieved through nginx load balancing but rather by redirecting to different servers based on request (e.g. file name or key).
For shared storage solution, you can use, for example, NFS. There are many resources going into deeper detail, for example https://unix.stackexchange.com/questions/114699/nfs-automatic-fail-over-or-load-balanced-or-clustering
For duplicate upload solution, you can either send file twice from client or do it server side with some code. Server side solution has the benefit of single file traffic from client and sending to second server only on fast network. In simple case this can be achieved, for example, by receiving file in a servlet, storing incoming data to disk and simultaneously upload to another servlet on the second server through http or other protocol.
Note that setting up any of these options correctly can involve quite significant effort, testing and maintanance.
Here comes S3, ready to use distributed/shared storage, with simple API, integrations, clients and reasonable price. For simple solution usually it is not cheaper in terms of $ per storage, but much cheaper in terms of R&D. It also has the option to serve flies and content through http (balanced, reliable and distributed), so you either can download file in client directly from S3 hosts or make permanent or temporary redirects there from your http servers.