My take on Logging Levels

A long time ago, while developing a realtime server for Verint, the system's architect devised a great document called 'logging policy'.

It explained how a log message should look like, which information they should contain, and elaborated the rules for each log message level: For example: "There is no such thing as a 'Good' warning. Do NOT put 'Server is now up' messages in warning level".

Back then, the common practice ranged more than five levels, from critical to verbose.

At least at the beginning of development, I found that, though it's nice to do so, right now the most effective number of logging levels is 2. Debug mode and production mode.
Production mode should contain high level log events (Flow events, processing metrics) and errors, debug - the rest.

Logging is one of the strongest maintainability tools for your server. However, keep it simple, or you'll drown in misleading information.