Setting up nginx as a backend?

Question

Nginx

upstream backend {
    server 127.0.0.1:9000;
    server 127.0.0.1:9001;
    server 127.0.0.1:9002;
    server 127.0.0.1:9003;
    server 127.0.0.1:9004;
    server 127.0.0.1:9005;
    server 127.0.0.1:9006;
    server 127.0.0.1:9007;
    server 127.0.0.1:9008;
    server 127.0.0.1:9009;
  }
  location ~ \.php$ {
    root html;
    fastcgi_pass	backend;
    fastcgi_index 	index.php;
    fastcgi_param 	SCRIPT_FILENAME	$document_root$fastcgi_script_name;
    include		fastcgi_params;
  }

What are the pros and cons of such settings and how to do it right? specifically interested in the number of backends.

Answer 1

I thought the absolute address to the directory is written to root.
Should location not be inside the host declaration?
Hmm... does this configuration work?