Business Continuity Planning for Data Centers and Systems: A Strategic Implementation Guide

Chapter 10. Tier 4: Basis of Design

This chapter provides a shorthand checklist for resilient redundancy for mission-critical facilities with survivability in mind. Because there have been many mission-critical seminars and white papers, consultants have become familiar with phrases that articulate what a design is and is not. This is not perfect and is still subjective in some areas. However, we are collectively better off now in grouping and recognizing a design and its relative integrity, cost, and duration to design, build, and maintain. In the early stages of site selection, we spend most of our time articulating the differences and values of the various improvements that make up the various tier levels. Then we spend time understanding the differences between Tiers 2 and 3 and the capital expenditure and operations expenditure to support them and discussing what peers are doing. The improvements associated with Tiers 3 and 4 are relegated to mission-critical facilities only or to users who can demonstrate, via the business impact analysis, that they can lose enough money by the moment to support such an investment of capital and human resources. Concurrent maintainability is the theme for Tiers 3 and 4 in anticipation of required maintenance and failure of some components of the electrical and mechanical systems. Purists do not embrace the use of Tier 3 plus or Tier 4 minus solutions; they believe the requirement either is or is not Tier 3 or Tier 4. If a business impact analysis ...