Data centre is a cluster of computer servers that are used for storage and distribution of data. It gives security, connectivity, and centralized storage options. Data centre is best for businesses that need a lot of networking tools and access to more than one server at a time. All data centres do not provide same features. Standards of data centres are described through Four-Tier system. This classification method was developed in 1995 by Uptime Institute to differentiate facilities through design features, like redundancy, building features, and definite uptime. This classification approach helps potential tenants to select facilities that can accomplish their demands, compliance, and operational requirements. Uptime Institute states that 500 services are certified in 66 countries with specific standards. In this article, we have described worldwide standards for data centres that are shared across all tiers.
Tier I
Bare minimum is offered by data centre Tier I in the form of infrastructure adjustments. It has single electrical path for cooling and powering equipment. Failure of one component means to face downtime. Facilities of Tier 1 provide minimum 99.671% uptime which means downtime of 29 hours on annual basis. It is suitable for small business, however, it is not ideal for an enterprise that demands no interruption during its operations.
Tier II
Just like Tier 1, data centre Tier II has one pathway for cooling and power allocation. Facilities are provided with backup generators as well as cooling systems to work in case of power outage. It has uptime 99.741%, which means, a downtime of 7 hours per annum. As compared to Tier I, it is more dependable system.
Tier III
In data centre Tier III, redundancy is highlighted more than all other factors. It is developed on infrastructure N+1. At Tier III, data centres are well equipped with tools required to work on regular basis. Moreover, it has safe backup of all components. As compared to first two data centres, Tier III has uptime 99.982%. It is perfect for large scale companies, as downtime is just 1.6 hours per annum, that means negligible disruption while maintenance is performed.
Tier IV
It has a completely redundant environment that has potential to work even if some fault occurs. Tier IV has infrastructure N+2 that means to have backup generators, UPS systems and two additional cooling systems. For this data centre, estimated uptime is minimum 99.995 percent. Its downtime ratio is just 0.8 hours in a year. Tier IV offers less disruption than Tier III data centre. Usually such facilities are selected by tech giants, state-run governments, and large scale companies that need maximum accessibility.
Conclusion
Irrespective of uptime or downtime ratio, companies do not always require round the clock availability to achieve their goals. Four systems are compared and Tier IV seems an ideal, bulletproof, and completely redundant system, whereas Tier I is reasonably priced option. Companies must consider their IT requirements, and budget while selecting data centre to get consistent solution by paying low operational cost.
