Issue link: https://www.e-digitaleditions.com/i/1107553
8 I ICT TODAY COMMISSIONING TERMS The practice of commissioning a data center project has been evolving for over 25 years. Given the different disciplines in the construction of a data center (Figure 1), commissioning has common themes and definitions. Commissioning is critical in all aspects of the data center design/ build plan. This article focuses primarily on the ICT cabling piece of this complicated puzzle. The commissioning plan describes all aspects of the commission process. The plan defines the guiding principles detailing schedules, defined responsibilities, full and accurate test documentation, and functional performance guidelines. Furthermore, commissioning identifies potential issues before they become a problem. The realized benefits of commissioning include less repairs, fewer moves, adds and changes (MACs), and unplanned FIGURE 1: Shown is a data center under construction and the data center's "white space." downtime prevention. It is soon recognized that liability costs and the resulting damage to a business reputation far outweigh the costs associated with a comprehensive commissioning plan. DATA CENTER CLASSIFICATIONS Data centers are defined into five classes per the BICSI non-profit standards body: • Class-0 (no redundancies, no backup power) • Class-1 (no redundancies to protect IT load from failure) • Class-2 (component level redundancy in key systems) • Class-3 (concurrently maintainable) • Class-4 (fault tolerant to most events, except for severe building damage/destruction) The Telecommunication Industry Association (TIA) non-profit standards body uses Rated 1-4 criteria to define data centers, while the Uptime Institute, a for-profit commercial organization, uses proprietary Tiers I-IV. Data center definitions, based upon "uptime" or "availability" and derived from TIA and Uptime Institute formulas, indicate (as does BICSI) that the higher the number the better. Per TIA and the Uptime Institute, a Rated-1 or Tier-I data center has a minimal 99.671 percent uptime and 28.8 hours of downtime per year. Rated-3 or Tier III is a data center with 99.982 percent uptime and no more than 1.6 hours of downtime annually; and one Rated-4 or Tier IV has 99.995 percent uptime and 26.3 minutes of annual downtime, approaching a similar result to that of BICSI's Class-4 fault tolerance. What happens when a backhoe accidentally digs up an OSP backbone? Or when a contractor