Want to log all request|response where backend response status > 2XX

[#1]

Hello

I have what I think is a simple question. I am pretty new to Apigee and am learning fast... but reading the documentation, I am just a little fuzzy on how best to perform the following task:

when we get a response from our backend other than a 2XX status response (4XX, 5XX), I want to write both the request (sent to the backend) and the response (send from the backend) to a log file. We have a private cloud.

I am reading all kinds of stuff on fault rules, raise fault policies, and message logging policies... but I am looking for a best practices type of scenario here.

Thanks

Don