Tip to Tail
I once knew a guy that used to tell me “never confuse sales with delivery”. Apparently many of his clients didn’t share his liberal definition of cognitive dissonance, so he currently wears an orange jumpsuit to work every day. Perhaps his motto should have been “language matters, so always be sure you and your provider are reading the same book”. I think this is particularly good advice for today’s mission critical data center customer.
If you’re a regular reader of this blog (thank you), you know that I believe strongly that if you say you do it, certify it. Unfortunately, most providers still don’t, and it’s up to the customer to gather the preponderance of evidence necessary to ensure that they understand exactly what a provider will deliver to them. In this current environment of caveat emptor, where what is said can often stretch the bounds of the term “liberal definition” until they break, understanding the shortcomings of a provider’s claims can save you from some very uncomfortable situations later.
It’s 2N/N+1…Kind of
In the world of engineering, N is the number of components of a system or subsystem that are required for normal operation. The simplest and most operator friendly form of providing redundancy is have two identical sets of components to provide normal operation. Think The Matrix – “Blue pill or red pill?” Pretty easy to understand, even at 2 in the morning during a blizzard. This is what 2N provides. This capability extends to maintenance operations, where a unit is taken off-line for regular service without bringing the entire facility down. In a 2N system design, there is no single point of failure in that particular system. The value of a 2N design is that it provides the easy operations scenario for concurrent maintainability.
An Uptime Tier III certification of a constructed facility tests the systems to ensure the holistic and complete ability of the facility to provide concurrent maintainability. In other words, the certification involves intrusive operation of the facility while in a myriad failure and operation modes to ensure that it operates like the design dictates without a single point of failure. Now, several providers claim that there is no need to certify the facility. I beg to differ. Many of these providers casually throw around 2N or N+1 design in marketing and sales pitches. It reminds me of the line from the Wizard of Oz – “Pay no attention to the man behind the curtain!”
In the data center industry, mission critical facilities live and die on the deployment of the following electrical components:
– Programmable Logic Controllers (PLC)
– Output Boards
– Mechanical Boards
When evaluating the 2N claims of potential providers that do not get a certification from Uptime, these are the key areas of focus, and the majority of “misleading” assertions of 2N design. The following are some of the most common “faux” 2N claims:
1) “It’s 2N”: The PDUs are dual corded but they both go to the same UPS. Oh, and by the way, you are not allowed to look at my as-built one-lines.
2) “It’s 2N”: The PDUs and UPS are 2N but the single set of switchgear that ties them together isn’t.
3) “It’s 2N”: Except there is only a single PLC on the switchboard. A Homer Simpson “DOH!” moment indeed, when that PLC fails…
Designs advertised as N+1 can be found to be lacking, as found when examining the following “slightly misleading” assertions:
1) “It’s N+1”: Multiple PDUs and UPS that resolve into a single static switch for the UPS.
2) “It’s N+1”: The single mechanical board deployed would beg to differ.
3) “It’s N+1”: If that’s true, why does it have only a single UPS output board.
The fallaciousness of these claims is exacerbated by the fact that even in data centers that feature a true 2N design from tip to tail, components fail. The issue for mission critical end users between a real 2N facility and a “loosely defined” counterpart is the difference between making an inevitable failure manageable or devastating.
The best way to ensure that you are getting a data center that matches its advertised design is to insist that it be constructed certified by the Uptime Institute. As I’ve discussed before, there are many providers who claim to offer Tier III certified facilities but what was actually built does not correspond to their certified design. Your facility should have both certifications.
If your provider proposed data center isn’t certified, they should, at a minimum be willing to share their one lines (not a block diagram) of that specific facility. You should also insist on reviewing their sequence of operations for that design as well. Any reluctance, or refusal to show you these documents should be your signal look elsewhere for your new data center. If you want mission critical space with concurrent maintainability, “trust me” shouldn’t cut it. Nor should the argument that “Do you think these other customers would be in this space if we weren’t 2N?” Answer that question with a “Yes, I can envision that.”– Because it happens.
So you may say, “Chris, can a provider have a concurrent maintainable facility without an Uptime certification?” Absolutely. However, when you do your due diligence on that facility, you better make sure that they are an open book when It comes to proving that is the case. Your SLA may mean something during negotiation, but it is as valuable as used toilet paper when you are waiting for your service provider to replace the recently fried bus on the single output board for the 2N UPS. Have fun with that conversation with your CEO…
Not every company requires a mission critical facility, and there are plenty of providers that are capable of meeting their needs. Like a pyramid, however, the universe that can deliver one for businesses whose applications demand the maximum degree of reliability possible narrows dramatically. This situation becomes even more constrictive when many of them are asked for the documentation to support what they are telling you. The important thing to remember, as evidenced by my incarcerated acquaintance, is that there is often a huge difference between sales and delivery.