On the relevance of efficient, integrated computer and network monitoring in HEP distributed online environment

Large Scientific Equipments are controlled by Computer System whose complexity is growing driven, on the one hand by the volume and variety of the information, its distributed nature, thhe sophistication of its trearment and, on the over hand by the fast evolution of the computer and network market. Some people call them generically Large-Scale Distributed Data Intensive Information Systems or Distributed Computer Control Systems (DCCS) for those systems dealing more with real time control. Taking advantage of (or forced by) the distributed architecture, the tasks are more and more often implemented as Client-Server applications. In this frame- work the monitoring of the computer nodes, the communications network and the applications becomes of primary importance for ensuring the safe running and guaranteed performance of the system. With the future generation of HEP experiments, such as those at the LHC in view, it is to integrate the various functions of DCCS monitoring into one general purpose Multi-layer System.