A Tier 3 data center is the second-highest certification in the Uptime Institute’s system of classifying data center performance into four tiers.
- N+1 redundancy. Tier 3 data centers provide N+1 redundant power and cooling distribution paths to allow for routine maintenance without downtime.
- 72-hour outage protection. Three days of independent power that is not connected to any outside source is required.
- No more than 1.6 hours of downtime per year. This is the maximum amount of downtime allowed in a year for maintenance and emergencies.
- 99.982% uptime. Some downtime may occur for unplanned maintenance and emergencies. Customer-facing services may be impacted.
Tier 3 data centers are the most common certification by the Uptime Institute and are often utilized by organizations larger than a typical small- to medium-sized business. Tier 3 providers feature many of the offerings of Tier 4 providers but guarantee slightly less uptime and are not completely fault-tolerant.