Raised floor vs Slab (2)

So you want to build a data center (DC), huh? Or maybe not. Maybe you just want to rent space at a DC  for all of your, well, data, of course. Either way, as we examined last week, you’ll want to turn your eyes downward at some point in the decision-making process. When you do, you’ll want to know what you should be looking for. Do you? If you read the first part of this blog that we posted on Friday, then you know there are two basic options when it comes to flooring: slab or raised access.

To quickly recap, for what felt like a millennium, the raised access floor ruled the data center world with nary a challenger. It evened out the normally uneven slabs below centers, which led allowed for symmetrical rows of cabinets; it made it easy for managers to hide all of those huge cables and connectors of the old days neatly away and out of sight; and it offered a way to spot cool servers. But then things changed. You’ll have to read the entirety of the first blog on this topic for the full details, but basically technology moved forward — as it is wont to do — and bred new needs and requirements and allowed for new efficiencies that made the raised floor look like a dinosaur. That’s how slab wriggled its way back into the conversation.

Slab to the Rescue?

The majority of server farms are still constructed with a raised floor as part of the plans. But IT isn’t a democracy; the majority doesn’t necessarily rule. Here’s another cliché for you: what’s old is new again. Slab floors in centers may actually be the wave of the future.

Don’t believe it? Maybe this will convince you: the Uptime Institute last year found that only around 48 percent of companies were planning to build centers with raised floors. Right now it’s estimated that 90 percent of centers are making use of raised access floors, but that number could be cut in half one day soon if Uptime’s numbers are to be believed.

So why is that? There are several main reasons. As mentioned, one of the old benefits of raising the floor was the improved cooling efficiency that allowed managers to move away from freezing entire centers and instead get the cold air only where it needed to be. It was a great solution for a great long while, but some of today’s hardware is as high density as 8-10 kilowatts (or more) per rack. That means massive amounts of cooling are needed, and obstructions like cabling beneath the floor can hold back a center’s ability to properly cool its racks.

Then there’s the cost issue. Everyone wants to save money wherever they can in business, and the data industry is particularly obsessed with running the most efficient operations possible. The simple reality is that bolting down racks to concrete is a heck of a lot cheaper than constructing a raised access floor for them to sit on. Of course, not using a raised floor means you’re probably going to have to run overhead cables and cooling ducts, which has its own expenses. Still, that’s usually going to come out cheaper than building a second floor.

And have you ever actually lifted up a few tiles at a data center and seen what’s beneath? Sure, the cables are probably neatly routed and bound, but what else are you going to see? Dust, dirt and debris and plenty of it. Cleaning below a raised access floor is an extreme headache, which means it’s often filthy dirty in the area beneath raised floors, which is not exactly an attractive attribute of a place that’s going to be housing tons of expensive hardware that stores an incredible amount of important data. Additionally, raised spare parts and junk tend to get stashed under the tiles as time goes on. Nobody really wants to do it, and everybody thinks they’re going to be better than that when they’re building their facility, but most fall prey to stashing things out of sight and out of mind as the years go by in a work environment in which free time for finding a better storage solution is at a premium.

When things are hidden down there, it may be difficult to ever find them, and hiding “stuff” down there makes it hard to find things you’re actually looking for. What happens if there’s a security threat like an access point or a moisture leak or wall breach below the floor someplace? Operators are going to have a heck of a time trying to find it, that’s what – especially if a bunch of junk is being stored down there.

Raised floors aren’t invincible, either. It’s true enough that they can be designed to bear almost any load imaginable. But what if a facility’s designers imagine the wrong load? Scalability is huge in the DC world, and it often comes at unpredictable rates. If a center grows at an unexpected exponential rate, and they sometimes do, then safely deploying more hardware on top of a floor that wasn’t designed for it can lead to big problems. It’s also possible that a center will start using equipment from different manufacturers or some future technological direction of servers will lead to them weighing more than those originally planned for a center. Finally, the whole thing can be further compounded by seismic activity.

The final, and perhaps most important, reason why many DCs are moving away from raised floors and towards slab ones is power. Forcing cold air down under a faux floor and guiding it back up to cool off equipment takes a ton of power. It’s not a natural airflow, and making it happen is costly. Alternatively, putting the cooling system up in the ceiling and allowing cold air to naturally fall down the way physics intended it to makes for huge power savings. Cooling down hardware is one of the largest power drains on DCs, and doing it from above instead of from below greatly reduces the need to use massive amounts of fan power to make it happen.

“Anyone designing a new data center now with raised-floor cooling is being environmentally irresponsible,” Schneider Electrics Senior VP of Innovation Neil Rasmussen recently wrote on Data Center Dynamics. Running greener and more efficiently is a great thing, but it unfortunately isn’t always practical for all DCs.

Raised Floors Still Have Advantages

We’re likely to continue seeing more and more new centers choose slab floors for all of the reasons listed above. However, there are still a large minority of centers being built with raised access floors.  One reason is that installing overhead cooling and wiring systems is expensive, and may outweigh the power savings for some smaller centers. Raised floors may also be the ideal solution for DCs in which racks need to be routinely rearranged.

Every DC is unique, and raised floors still make sense for some, so don’t expect them to completely disappear from the data center world overnight. But don’t be surprised when slabs slowly take over, because they’ve already started to.