Data Center Tiers, No Tears, No Plus or Minus



Press releases, promotion material and website of some data center service providers, often carry this term Tier 3+, or Tier 4-, or Tier 3.5. This is intended to give the reader an impression the facility is of a higher level of resiliency in terms of design or implementation.

What’s in a Tier/Rated/Facility-Class

Tier Classification System is trademark by Uptime Institute (UTI). In a nutshell, UTI will assess and award the appropriate Tier level if a data center facility owner or private data center client engages UTI to perform such an evaluation. UTI issues the Tier levels in roman numerals I/II/III/IV.

The Telecommunications Industry Association, which is an American organization that issues telecommunications cabling and telecommunications facility standards, issued ANSI/TIA-942-A which is titled “Telecommunications Infrastructure Standard for Data Centers”, of which the latest 2014 edition contains three informative annexes (D, E, F) on data center space considerations, site selection and building design considerations, and data center infrastructure rating. Using the informative annexes of TIA-942-A, a data center facility can be rated according to four categories (Telecommunications, Architectural and Structural, Electrical, and Mechanical) to be Rated 1 – Basic, 2 – Redundant Component, 3 – Concurrently Maintainable, and 4 – Fault Tolerant.

The EN-50600 standard classify a data center in a similar manner to TIA-942-A, but adds a Facility Class 0, i.e. FC-0, while FC-1 through to FC-4 are essentially the same as TIA-942-A’s Rated 1 through to 4. FC-0 is a basically a computer room with server directly connected to utility power without backup power.

Plus? Minus? 3.9?

In any of the abovementioned standards, there is no mentioned of a +/- to any of the rating or classification. None of the standard gives room for partial, fractional, or + / – rating modifier, neither do UTI for their Tier award. So a data center can only be awarded certification that stated Tier III, or Rated 3, or Facility Class 3, but not 3.5, or 3+, or 4-.

Dig Deeper Below that Claimed Rating

If the particular data center facility that announced that they have a Tier 3+ data center facility, checked whether were the rating issued by any competent third party or an technical audit firm. No competent third party or technical audit firm should issue such a non-standard rating.

Such Tier 3+ or Tier4- are self-proclaimed rating in an effort by that data center facility to signal that their facility has features better than Tier 3 or just a tad below Tier 4. But, without a competent third party to evaluate whether that particular data center facility meets, say Rated 3 in the categories of Electrical and Mechanical in the first place.

In the case that that particular data center facility is evaluated by third party to be Tier 4 in the category of Electrical and Tier 3 in the category of Mechanical, then it is to be given at the lowest common rating, i.e. a Tier 3 rating.

What should potential Data Center Client Do

If the Tier level is self pro-claimed without the word certified by, or usually the words are like “our latest data center is designed to Tier 3+ resiliency”, then it is most likely not certified by any third party and the potential data center client should insist on a competent technical third party to evaluate the technical attributes of the data center if they want to consider collocating their IT equipment with them.

  • Ask the site to substantiate the self proclaimed rating using third party

We should just disregard the +, and in our mind de-rate those – or those with the decimal, i.e. if we see a Tier 4- or a Tier 3.5, we should just consider such a data center facility to be designed to Tier 3 and if we decide to consider such a data center facility, to engage a competent technical third party or better yet is to insist that the facility owner engages a third party and bears the cost.

The data center facility may dangle the Tier 3+ as a indirect indication that their site is of high quality which imply justifying a higher premium. However, the potential client should have a site selection process that have clear requirements of a data center facility and do not attach any score to the site unless it is justifiable through third party certification. Having a certification should be viewed as hygiene factor. The evaluation criteria should request for data on the technical, business/financials, and operations attributes which allows for normalization and comparison across the different shortlisted sites.

  • Tier level and Suitability to client business IT needs

A data center’s main function is to house IT equipment. Whether that IT equipment requires fault tolerant power and cooling support or it is only a test environment that can take a rung or two lower in terms of power and cooling resiliency set-up, then a data center facility that allows you to have a private suite to house critical production IT equipment in a Tier 4 set-up, and a small suite or even cage in a shared Tier 3 co-location hall is more suitable, thereby giving rise to a combined set-up that meets both the business need and best bang for the buck. This set-up is also called multi-tier or flexible-tier set-up. Not all data center facility can meet this need or the cost is higher because the base set-up of that particular data center facility will involve heavy re-work compared to one that is ready from day-one to be flexible in this aspect.

  • Do not over rely on the Tier level rating

Tier 4 data center facility doesn’t mean no downtime. Its fault tolerant but trouble rarely comes once, it may come twice and thrice. And it doesn’t take power or cooling issue to bring down a critical IT system within a data center. Human can cause problem. Or in the July 2016 incident with the Singapore Stock Exchange’s more than 5 hours unavailability of its trading system, it’s a hard disk failure that drag down the entire trading system. A distributed denial of service attack, or a telecommunications problem can bring down IT.

  • Evaluate using a comprehensive set of evaluation criteria

The things that potential data center client should do is look beyond the rating level, as whether a data center facility is designed, implemented, and certified to a data center rating level is just one facet of a data center facility’s suitability to its IT needs. There are multitude of other factors including telecommunications facilities, data center facility operations system, competencies of the facility people, among others that counts towards a resilient IT operations in a data center.

  • 24×7 on the ball operations and Watch that capacity

Sometimes, the Tier rating level will drop as the designed capacity is breached and N+1 suddenly because N and the site loses the redundancy ability. Concurrently maintainable or Fault tolerant electrical design do means that when 1N of the 2N UPS is taken offline to have servicing performed, the planning and execution of such maintenance should have the proper procedures (SOP, MOP, MOS) and backup or roll-back plans (RA). You want to minimize risk and risk window of UPS problem when the other set of UPS is taken offline for maintenance. You should also not allow the UPS maintenance and backup generator maintenance to take place at the same time because this doubles the risk that when the remaining 1N UPS fails and then the generators are on manual, you will be forced to rely only on utility supply. The maintenance should be during non operations hours. All these things comes into play and the vendor experience is very important.


Data Center Tiers, No Tears, No Plus or Minus

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