Explain: Tier 1 / Tier 2 / Tier 3 / Tier 4 Data Center

Q. What is data center tiers? What is tier 1 data center? Which tier / level is the best for maximum uptime?

A. Tier 1 to 4 data center is nothing but a standardized methodology used to define uptime of data center. This is useful for measuring:

a) Data center performance
b) Investment
c) ROI (return on investment)

Tier 4 data center considered as most robust and less prone to failures. Tier 4 is designed to host mission critical servers and computer systems, with fully redundant subsystems (cooling, power, network links, storage etc) and compartmentalized security zones controlled by biometric access controls methods. Naturally, the simplest is a Tier 1 data center used by small business or shops.

  • Tier 1 = Non-redundant capacity components (single uplink and servers).
  • Tier 2 = Tier 1 + Redundant capacity components.
  • Tier 3 = Tier 1 + Tier 2 + Dual-powered equipments and multiple uplinks.
  • Tier 4 = Tier 1 + Tier 2 + Tier 3 + all components are fully fault-tolerant including uplinks, storage, chillers, HVAC systems, servers etc. Everything is dual-powered.

Data Center Availability According To Tiers

The levels also describes the availability of data from the hardware at a location as follows:

  • Tier 1: Guaranteeing 99.671% availability.
  • Tier 2: Guaranteeing 99.741% availability.
  • Tier 3: Guaranteeing 99.982% availability.
  • Tier 4: Guaranteeing 99.995% availability.

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98 comments… add one
  • Teja May 27, 2014 @ 18:22


    if any one wants to know about DATA CENTER knowledge, TIER standards, any queries, understanding on starting up Data Center. What Infrastructure to be used, Monitoring, Certifications, kindly contact me. thnx. Teja

    email: career14cni@outlook.com

  • Daniel Jun 12, 2014 @ 11:30

    How many racks can be kept at maximum inside Tier I infrastructure.?

    • Scott Payton Jun 22, 2014 @ 20:30

      The number of racks is not a function of the Tier of the DC.
      If you would like to discuss this further, please post to Data Center Discussion forum on http://www.tek-tips.com

  • shareef Jan 8, 2015 @ 6:37

    please send the solution for • Tier 1,Tier 2,Tier 3 , Tier 4

    what are requirement and best practice to be used

    • Scott Payton Jan 8, 2015 @ 7:42

      Your question is too vague and there are multiple standards, and “Tier” doesn’t mean the same across all of them. For a starting point, please see my discussion form “Data Center Discussion” on tek-tips, where you can find information, and post follow-up discussions (http://www.tek-tips.com/threadminder.cfm?pid=1786). I no longer make technical replies in this thread.
      Best regards,

  • Sundar Mar 7, 2015 @ 16:24

    Great post, very crisp. Keep up the good work.

  • Mudessar Rahim May 12, 2015 @ 14:11

    I have to work on an assignment.
    I am asked “what are different tiers of data centers? Explain in detail.
    Also design a tier1 data center for a nationwide cellular company then gradually upgrade to tier2, tier3 and finally tier4, sharing the upgradation steps.’
    Can I get some help in the matter?
    Mudessar Rahim

  • RR May 14, 2015 @ 18:03

    what is the average ratio between T1,T2 and T3 for a software support organization

  • Razi Abbas Oct 14, 2015 @ 12:45

    great job….very nice to have all information I was looking for in one place……thank you…..

  • Damini Baichoo Mar 6, 2016 @ 17:35

    I’m preparing a business proposal to a telecommunication company who wants to open a subsidiary in Africa. So, I was requiring your expertise and knowledge as a guide in setting up of a Tier 4 Data centre. What are requirements and costs involved? And how could we assess the risks?

  • Stefan Aug 21, 2016 @ 22:30

    What is the definition of a “capacity component” (as introduced in Tier II)?

  • ammar Nov 30, 2016 @ 13:39

    I am going to do the electrical design for TIER 4 data center. Can anyone please send me the electrical single line diagram so i can have an idea about TIER 4 redundancy requirements.

  • ammar Nov 30, 2016 @ 13:40

    I am going to do the electrical design for TIER 4 data center. Can anyone please send me the electrical single line diagram so i can have an idea about TIER 4 redundancy requirements. You can send me the files on the below id.


  • apeksha Mishra Dec 20, 2016 @ 18:59

    Hey could you help me with the information regarding the pricing of one data center in relation to space as well as cost.

  • Mandar Panchal Jan 27, 2017 @ 17:58

    Thank you all for such helpful information.

    I am Data Centre engineer since last 2 year.I want to make carrier as Data centre consultant, can any one guide me which organisation offers certification of consultant ?
    Is CDCP course is reuire for become consultant ?

    Kindly update me for this.

  • Donald Feronti Mar 1, 2017 @ 20:02

    What is your opinion on having the critical areas of data centers professionally cleaned? Example is having the raised floor cleaned and vacuumed with high filtration environmental vacuums and lint free wipes . Cleaning under the floor space and wiping down the equipment cabinets not touching the critical components to remove particulate contamination in the data center. Do you think this is a necessary process to maintain a data center. Or I guess I should ask do you do this or recommend this for data centers?

    Thanks for your time and input.

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