Nginx as frontend for PHP-FPM backend on another server. Where to keep static?

Question

PHP

Suppose I have two servers / virtual machines
On one nginx, on the other - php-fpm and mysql
Suppose I proxy requests to php through nginx to the second server
What to do with requests to statics? Also proxy and hold on the backend? Or synchronize (how?) two folders on the backend and frontend, and only proxy requests to php, and give the static from your machine? Or set up caching (how?) on your disk of static received from the backed?

Answer 1

Amazon s3 seems to be inexpensive.