It's not your father's data center.That sums up both the recommendations of our Data Center report as well as the findings of our survey. Roughly half of those we polled say it's either certain or likely that they'll have to upgrade their data center power and cooling systems within a year, and another quarter are on the fence. The conundrum facing most organizations is just how to go about that upgrade. Dad's data center might not do the job for modern servers, storage, and networking gear—all of which continue to consume more watts per square foot—but building a new facility can be eye-poppingly expensive.

For most organizations, there's little choice. The need to store and process ever-larger quantities of data in new and more complex ways shows no sign of abating, and while we've preached the value of server consolidation and storage management, sooner or later Moore's Law catches up with you and it's time to remodel or build new.

While power and cooling systems continue to be a primary concern, two interesting facts came to light when we asked about space constraints. First, well over half of respondents report having sufficient room to grow in their existing facilities. This is as expected; servers and storage systems continue to pack more into less space, so increasing raw floor space isn't the driving factor in data center improvements. What we didn't expect was that almost a quarter of respondents say they're using facilities that aren't data center grade to meet their needs.

While we didn't explore the issue further, it seems likely that these respondents either work for smaller companies or are telling us about facilities in remote offices. It appears that the "data center in a box" products—those refrigerator-sized systems that contain the necessary cooling and uninterruptible power supplies sufficient for 30 or so 1U systems—may have significant appeal.

That statistic may also hint at what's really driving data center consolidation. A variety of concerns, ranging from compliance to security to reliability and availability, require better system management that comes from moving departmental and remote servers back to the data center.

REAL IMPROVEMENT
While the need for better data center facilities is clear, what constitutes "better" is less clear. Should servers be specialized, or should they be as generic as possible? Are blade systems the way to go, or do they represent one more form of vendor lock-in? Is DC power the way to cut the electric bill, or is it more hassle than it's worth? Can raised floors do the job, or are they outdated? The list of questions seems endless, but it's quite clear that just building the same style facilities that we built just five years ago isn't a good idea. Perhaps the biggest issue to tackle is cost.

Most data center power systems were built to supply only 50 watts per square foot, but many analysts now recommend as much as 500 watts per square foot. That tenfold increase in power systems—including UPSes and generators—and cooling systems makes this by far the most expensive part of building a data center. If you're looking to build a Tier IV, "five nines" data center, as defined by the Uptime Institute, the power and cooling systems can run you as much as 50 times the cost of the building itself. And the yearly power bill if you use the full capabilities of the 15,000-square-foot facility described in our chart on p. AB2: $13 million per year in California, or almost five times the cost of the building.

While these numbers are for new construction, retrofitting existing facilities will be equally expensive—provided you have the space for additional water chillers and room in wire chases for the new power cabling.

Given the costs of nonconstruction infrastructure and the size of the electric bills, it makes sense to question every assumption about physical design. One of the design principles that's been called into question is the use of raised floors. There's good reason for that: As racks fill up, raised floors can become problematic. Just six years ago, the average power consumption per rack was less than 3 kW. Today that number has moved closer to 7 kW per rack, with high-density blade systems drawing 30 kW or more per enclosure. No raised-floor cooling system was designed to handle that. But it's not just the cooling system that argues for something other than a raised floor.

As systems require more power and cooling, they're also becoming heavier. So while you may need a clear 3-foot air gap to supply the needed airflow for cooling, such a raised floor will likely require special bracing to handle the weight of a full rack of systems, which can range from one-quarter ton to more than one ton per fully populated rack. Rather than relying on the raised floor to deliver sufficient cooling, in-row and rack-based cooling systems can significantly supplement or completely replace floor-based systems. These systems also have the advantage of being modular and delivering cooling to precisely the location it's needed—which can make them more efficient.

DC VS. AC
There's no doubt that you'll benefit from reconsidering data center best practices. One practice that we don't recommend reconsidering is the use of DC systems rather than the AC systems that currently dominate the data center.

Certainly there's demand for DC power for any business that requires NEBS (network-equipment building system) compliance, primarily major telcos. Telcos have used DC for years, primarily for reliability and the ease with which alternative power sources (batteries and generators) can be brought online to supplement line power.

Other industries have considered DC power, and every major server vendor makes at least a few DC-powered systems. One that specializes in DC servers is Rackable Systems.

There are some major concerns that typically dissuade the use of DC. You'll have many fewer systems from which to choose. Engineering DC power throughout a data center requires specialized knowledge—one loose bolt on a DC bus system and you may end up melting the bus bar. You have to put the inverters on the roof to avoid their heat generation jacking up the data center's cooling requirements. DC systems tend to be more expensive than AC systems, so the overall purchase cost is higher (though DC systems do use less energy, so the total cost of ownership may still work out.) Finally, while there are DC servers, switches, routers, and storage devices, there aren't DC computer room air conditioners. That means you'll end up with both AC and DC in your data center, and it would obviously be better to have just one power system. For these reasons, DC data centers haven't caught on for general use.