The Rated-4 data center classification is the gold standard of computer room facilities. The Uptime Institute defines a number of criteria that enterprise data centers and colocation facilities must meet in order to achieve Rated-4 status.
The biggest difference between tier III and higher rated centers is uptime levels: Rated-4 data centers provide 99.995% uptime, commonly referred to as 4 1/2 9's. This is accomplished through a hardened data center facility with multiple redundant systems that not only back each other up, but allow for concurrent maintainability. In another post, I wrote about how to decide whether you need a Rated 4 data center.
One of the Rated-4 criteria is a minimum three foot deep raised floor. Yet many IT professionals and outsource data center providers believe that raised floor does not belong in the standard.
Back in the 1960s, most of the mainframe equipment in the enterprise data center was cooled from the bottom up. Raised floor acted as a giant plenum or superduct that provided cool air to the equipment. Much of the equipment also was cabled from the bottom, so over time many raised floors became a jumble of electrical and communications cabling, impeding air flow and hiding the sins of installers and maintainers.
Today, virtually all equipment in small and large data centers is cooled from front to back. Raised floor is still used as a plenum, and is often used as the pressurized air input in a hot aisle/cold aisle configuration.
But more and more enterprise data centers and outsource data centers are switching back to solid floor with overhead power and cabling. The benefits of solid floor are lower installation and maintenance costs, more reliable floor loading, and cleaner cable and power management with better air flow. And many solid floor proponents also say that they can cool the densest implementations just as well in solid floor data center as in a raised floor environment.
The telecommunications industry standard mentions raised floor but does not condone or require them. TIA 942 compliant data centers don't require raised floor.
Do you think raised floor belongs in the Rated-4 data center criteria?