I'm using an old version of nginx (0.8) on centos as reverse proxy for caching POST requests in front of two upstream servers.
The servers are built for receiving post requests and returning media, sometimes 10 MB in size.

When the responses are small, nginx caches work fine. When I get a 2 MB response, nginx doesn't cache the POST response.

I tried increasing proxy buffer size and busy buffer size but it had no effect, how do I cache large POST responses in nginx?