The Physical Model provides a representation of the actual physical environment. Most of the managed environment is represented by logical objects, that is, objects that represent informational aspects of the environment rather than actual physical objects. Most of systems management is concerned with manipulating information that represents and controls the state of the system. Any impact on the actual physical environment (such as the movement of a read head on a physical drive, or the starting of a fan) is likely to only happen as an indirect consequence of the manipulation of the logical environment. As such, the physical environment is typically not of direct concern.
Apart from anything else, physical parts of the system are not instrumented. Their current state (and possibly even their very existence) can only be indirectly inferred from other information about the system. In the CIM, the physical model is a representation of this aspect of the environment and it is expected that it will differ dramatically from system to system and over time as technology evolves. It is also expected that the physical environment will always be very difficult to track and instrument, spawning the opportunity for a separate specialty, that of deploying applications, tools, and environments specifically aimed at providing information about the physical aspect of the managed environment.