How Modularity Works in Data Center Design
The term "modularity" refers to the practice of prefabricating units in manufacturing facilities under controlled conditions and then transporting those completed units to a separate site. The variable in data center modularity is defining the "unit."
At one end is the data center in a shipping container. That is, each container houses computer servers, along with wiring, power and cooling systems. Once assembled and pretested, they are loaded onto flatbeds, driven to the site and basically just plugged in.
Kevin McCarthy, associate vice president of AECOM, says that such solutions can be deployed one fully configured container at a time. "Once it arrives on site, the facility provides chilled water, power and communications to the container," he says.
Another version of modularity being seen at trade shows are modules with cooling and electricity built in, according to Paul Schlattman, vice president of mission critical facilities for Environmental Design Systems, Inc. "These modular containers typically hold up to seven racks," he says.
Schlattman says he sees those containers as serving customers who need a new data center application and have no capacity or swing space in their existing mission critical facility. He considers them a temporary fix until the company can build out a permanent solution. They also are valuable for disaster recovery applications and have been offered since the late 1990s.
A third level of modularity — and the one that currently is the most frequently built out — is to prefabricate certain components as part of an existing or even new data center infrastructure. A variant of this approach is to use the same modular component to provide the redundancy necessary for multiple modular systems, which is particularly valuable for large Tier 2 and Tier 3 data centers.
Here's how modularity works in the latter scenario: One separate electric infrastructure, called a catcher system, is the backup for up to four data modules. On those rare occasions that a glitch occurs or maintenance is necessary, one of those modules may need the redundant electric infrastructure that the catcher provides. The catcher system mirrors the module's electrical need and is designed to catch up to four separate systems. In a multistory server farm application, using a catcher system on each server floor allows maintainability with no downtime.
Modularity also can be applied to the mechanical and electrical infrastructure of large data centers.
"Basically, we define modularity as building the mechanical and electrical infrastructure off site and then reassembling it," says R. Stephen Spinazzola, vice president of RTKL.
Every level of data center can potentially benefit from modularity. For sudden need, temporary applications and unpredictable growth situations, container modules are practical. For campus environments, modules fed into a centralized chilled water plant and built around centralized power generation may be practical. For large Tier 3 and Tier 4 applications, modularity helps to bring down per-rack costs.
Wide Range of Applications
"Modularity makes sense in just about any application, to some degree, where the day one cost and efficiency are major concerns," says Bill Sewell, senior vice president and global data center market leader for AECOM. However, Sewell says he believes one of the best modular design applications is an enterprise data center capable of hosting both critical and non-critical business applications. "By designing the data center in modules, one doesn't overbuild the infrastructure for non-critical applications that can tolerate some outages, such as email or office apps," Sewell says. "At the same time, critical applications can be supported by Tier 3 or Tier 4 infrastructure to assure the proper level of availability."
Spinazzola believes modularity shines in Tier 3 or Tier 4 applications, particularly when it comes to chillers, generators and UPS systems. In fact, he believes the quasi-assembly-line approach, helps to reduce the cost per kilowatt and save time as compared to on-site built units.
"The factory-assembled chiller may even be better than a stick-built chiller plant," he says, "because it can be tested before it leaves the factory."