Step 3: Determining Availability & Redundancy
Understanding and determining the data center availability and redundancy is a critical part of the holistic design process, and one that can significantly impact cost. Critical to this is determining which of the Uptime Institute’s tier ratings best suits the business needs.
• Tier 1: Non-redundant capacity components with an availability of ~99.671% and 28.8 hours of downtime per year
• Tier 2: Tier 1 + redundant capacity components with an availability of ~99.741% and 22 hours of downtime per year
• Tier 3: Tier 1 + Tier 2 + dual-powered equipment and multiple uplinks with an availability of ~99.982% and 1.6 hours of downtime per year.
• Tier 4: Tier 1 + Tier 2 + Tier 3 + all components fully fault-tolerant including uplinks, storage, chillers, HVAC systems and servers with everything dual-powered and an availability of ~99.95% with 0.4 hours of downtime per year
Many businesses believe they need 100% uptime, 365 days a year, 24 hours per day -- essentially Tier 4. This may or may not be true for your business; but the initial cost to build a data center at each tier must be considered. Following are some conservative estimates of cost increases from tier to tier.
• Tier 1 to Tier 2: ~ 30% increase in project CAPEX
• Tier 2 to Tier 3: ~ 50% increase in project CAPEX
• Tier 3 to Tier 4: ~ 22% increase in project CAPEX
Big business with enormous data centers often create multiple data center “halls” that each meet a specific tier classification for ‘right size’ availability and redundancy. This tactic can save on construction costs and allows a business to achieve lower operational cost.
More detailed information on the data center tier ratings can be found by visiting the Uptime Institute’s website, www.uptimeinstitute.com.