According to a report recently published by IMS Research, the taken-for-granted 42U height of an enclosure or rack should no longer be taken for granted. Liz Cruz, an IMS analyst who studies data center infrastructure, conducted a six-month study and concluded that in both height and width, enclosures and racks are getting larger. Cruz cites "increasing server depths, more cabling within cabinets, the need for airflow management and the desire to maximize floor space within data centers" as primary drivers of these trends.
She says that shipments of 48U racks are forecast to grow an average of 15 percent annually for the next five years, while 42U-rack shipments will grow at 5 percent over the same time period. The catalyst for these taller racks' growing popularity is the desire for data center owners to limit the need for buildouts by maximizing floor space. They would rather grow up than out. Although 42U-height systems make up approximately two-thirds of today's shipments, that share will decline. Cruz notes, however, that cabinets are likely to get only-so-tall: "The growth may be limited to 45U and 48U racks, given the logistical limitations associated with racks of 51/52U or higher. Transporting and moving in racks of this size is made difficult by truck-height restrictions and doorway openings to most data centers. 48U cabinets may prove to be the practical limit to enclosure sizes for this generation."
And as much as data center owners would prefer their enclosures to grow up rather than out, they will have to do just that - grow out - at least to some extent. IMS explains the current standard enclosure width is 600 mm, but "going forward, shipments of 750- to 800-mm-wide cabinets will grow at nearly twice the rate of 600-mm cabinets. In terms of depth, the 1100-mm category currently accounts for the greatest share, but 1200-mm will grow faster than any other depth in percentage terms."
Greater computing densities at the rack level are the primary causes. These densities result in more cabling within enclosures and more heat generated in them as well. Those two realities are driving up the enclosures' width and depth, to accommodate cable management and airflow. Cruz comments, "Growth in power densities are not expected to level out anytime in the near future, which means neither will enclosure sizes."