Showing posts with label uptime institute. Show all posts
Showing posts with label uptime institute. Show all posts

Friday, December 16, 2011

Which is higher availability 2N or N+2?

Modular scalable solutions continue to drive our industry to improved efficiency and availability. Most know about modular cabling infrastructure, CRAC units with VFDs and scalable UPS technology, but did you know you could also have modularity and scalability with your chillers?

Most understand that modular solutions improve efficiency, but many believe that a 2N design is higher availability than a N+2 design. Not so fast, 2N is 2 component failures away from an outage where N+2 in a modular design is typically 3 components away from having reduced capacity. So why doesn't Uptime consider N+x designs for any of the critical components in it's tiering ratings? For that matter why isn't there a data center rating system that considers the improved availability of N+x designs?

Tuesday, February 26, 2008

Are the Uptime Institute's Data Center Rating Tiers Out of Date?

Let me start by saying I have the utmost respect for the Uptime Institute’s Pitt Turner, P.E., John Seader, P.E., and Ken Brill and the work they have done furthering the cause of providing some standards to an otherwise standard-less subject like data center design. However, as a data center designer I feel their definitive work, Tier Classifications Define Site Infrastructure Performance, has passed its prime.

The Institute’s systems have been in use since 1995, which is positively ancient in the world of IT.

In its latest revision, the Uptime Institute’s Tier Performance Standards morphed from a tool for IT and corporate decision makers to consider the differences between different data center investments into a case study for consulting services pushing for certification against their standard.

While the data their standard is based upon has been culled from real client experiences, the analysis of the data has been interpreted by only one expert company, ComputerSite Engineering which works in close collaboration with the Uptime Institute. Surely, the standard could be vastly improved with the outside opinion and influence of many of the, just as expert, data center design firms that exist.

Case in point, the Uptime Institute has repeatedly defended the notion that there is no such thing as a partial tier conforming site (Tier 1+, almost Tier III, etc.). They argue that the rating is definitive and to say such things is a misuse of the rating guide. While I understand the argument that a site is only as good as its weakest link, to say that a site incorporating most, but not all of the elements of the tier definition is mathematically and experientially wrong.

PTS’ actual experiences bear this out. Our clients that have all the elements of a Tier II site, except for the second generator, are clearly better than those with no UPS and/or air conditioning redundancy (Tier I). Therefore, if not for Tier I+, how do they suggest to account for the vast realization between the real availability of the two sites?

It is interesting that most data center consulting, design, and engineering companies nationwide utilize elements of the white paper as a communications bridge to the non-facility engineering community, but not as part of their design process. In fact, most have developed and utilize their own internal rating guides.

While I will continue to utilize their indisputable expertise as a part of my own interpretation in directing PTS’ clients with their data center investment decisions, I suggest that clients would be wise not put all of their eggs in the Institute’s basket at this point in time.

What is your outlook on the Uptime Institute’s Tier Performance Standards? Is the four-tier perspective outdated or is it still a meaningful industry standard?