Cached Response / Web Acceleration profile - Logging possibilities?

Hi,

 

I got a request for a new LB implementation, which will face high peak loads for short time periods - similar to a page that sells tickets for concerts.

 

We want to implement caching, so that some of the static content is served by the BIG-IP. Unfortunately, another requirement is that everything has to be logged for legal purpose.

 

So my question is - is there a possibility to log the requests/responses that were served by caching and not forwarded to the backend server?