1. What's the behavior of caches_pages when an action returns a
I'd like to only cache the page if the action renders, but *not* cache
It will serve the cached page straight away, no matter what, until the
cache has expired. If you need to do redirects, use action-level
caching with a before_filter.
2. Any solution for using caching with a cluster of web servers? The
sweepers won't fire on the other web servers
One solution is to use action caching everywhere and then use a
central memcached server as your fragment store. Whenever you expire
an action, it'll get expired on that server.