Why not both? Front end HAProxy splits traffic up to different sets of front end webservers, a set for dynamic content and a set for static content. The dynamic set has servers for PHP, Rails, Java, whatever you need. The static content is directed to a pair of heavy duty varnish servers that cache the content coming from a large, but relatively slow, fileserver. Database access can also be load-balanced through HAProxy over a couple of read-only slaves, with writes going to a single read/write master.
I was wondering if varnish does load balancing as well as haproxy to 2 bird one stone
why don't we have web over nfs yet? or 9p? plan9 style?
Sure, it can. You can also configure nginx as a load-balancing reverse proxy. And use nginx for frontends and backends alike. But I also like using the best tool for each job. Also homogeneity is a bad idea from a security perspective. That's why Netflix uses a whole bunch of different operating systems for a whole bunch of different jobs.
It depends on the situation. Scalability comes to mind. It's always good to keep any future growth into account when designing the infrastructure for a particular purpose. But sure, don't add any unnecessary complexity.
You are confirming kinda what I though insincively from experence!
