A CMI coding method, a CMI decoding method, a CMI coding circuit, and a CMI decoding circuit which do not adversely affect a main signal to be CMI-coded and which allow a high-speed asynchronous signal to be always transmitted by Coding Rule Violation, with a simple procedure and a simple hardware structure are provided. The metal tube has a first inner layer and a second outer layer, where the first inner layer is made from copper and the second outer layer is made from austenitic steel. One or more sets of operational features are added to the system based on a comparison between the determined levels of configuration of the operating server instances and minimum levels of configuration associated with the one or more sets of operational features.