How to Select IT Racks and Enclosures – Part 1

Type and Sizing Requirements

Proper housing of IT equipment facilitates routine maintenance and contributes to overall uptime. Securing expensive server, storage, and networking gear in racks helps protect it from physical harm, while enabling organized hardware placement and well-labelled cabling. Taking the next step to a full enclosure with roof, side panels, and built-in cooling and other features can provide the right operating environment for delicate IT gear, especially in high-density installations.

There is an almost overwhelming selection of rack and cabinet enclosure products on the market with an array of price points to match. To help you find the right one for your needs and budget, we’ll provide some guidance from Park Place Technologies engineers.

Open Rack or Closed Cabinet?

The first question centers on open versus closed housings, and it’s really a matter of cooling. Ambient cooling can be used in environments with less density, and this makes cheaper, open racks a possibility. Customers can choose between two-post and four-post rack formats. Some products—the two-post versions in particular—will require special floor mounting.

Wall-mounted racks are another choice for smaller installations. Most are good for up to 300 or so pounds of equipment, assuming the wall will support the weight. These systems can be a convenient option for an independent business interested in housing some networking equipment and a server or two somewhere other than a desk in the IT department.

A key downside for any open-frame rack is the lack of locking capability. This can pose a security risk depending on access allowed to the area, closet, or room in which it is located. If the equipment will be sited in a high-traffic or easy-to-access space, a full enclosure may be desirable.

As densities increase, there is usually no choice but to move from open racks to full cabinet enclosures. More density equals more heat, so it’s important to seek out structured cabling for improved air flow and active heat removal systems. For an extra level of security even in fully monitored data centers, many organizations select lockable cabinets or those with keycard access features.

Sizing

Once you know whether you want a simple rack or a more complex enclosure, you can start to think about size. Of course, the system needs to fit the room or closet where it will be placed. This means considering the floor space available, as well as any height limitations. And a sometimes overlooked point—measure the doorway. Enclosures should fit through, preferably upright.

Next up, consider the weight rating. Rack and enclosure capacities range from a few hundred to many thousands of pounds. Keep in mind, the floor of the facility also needs to be rated to handle the weight you hope to stack. It’s no good to select a rack that can hold 3,000 pounds if it’s going to crash through a ceiling.

Getting down to the specifics, most IT equipment is 19” wide, a standard set by the Electronic Industry Association, although actual rack/enclosure widths vary from there.

Heights are measured the unit, “U,” also set by the EIA. One U is 1.75” and will correspond to standard measurements for IT equipment. For example:

• Switches are usually 1U or 2U.
• Most traditional servers are 1U to 4U.
• Blade servers will often range from 5U to 10U or more.

To arrive at your size specification, total the height of the equipment you have on hand and add a reasonable amount of space for expansion.

For many enterprises, it’s tough to go wrong using 42U racks or enclosures and expanding rack-by-rack or cabinet-by-cabinet, as necessary. Smaller set-ups or those meant to fit odd spaces can make use of half-height racks and enclosures of 24U or even smaller desktop and wall-mounted units running 5U to 20U.

Why Go Bigger for Enclosures?

The most common server cabinet dimensions have historically been 42U with a 24” (600mm) width and 42” (1070mm) depth. There are, however, many other options available. Heights of 45U, 48U, 52U, and 58U can make the most of floor space in a data center with tall ceilings (and strong floors). Moreover, some organizations will go with 48” depth over the usual 42”, and widths of 28”, 30” and 32” are common as well.

Why upsize? Networking racks, for one, tend to be wider to house the cabling trunks (but are also shallower). Server racks tend to go deep to allow for good cable management at the back. Plus, there are various other reasons to choose bigger cabinets to make room for more features, including:

• Built-in airflow systems for better cooling
• Power distribution units (PDUs)
• Power monitoring systems
• Battery backups
• Environmental monitoring systems (e.g., temperature alarms)
• Device management with KVM switches

Size Isn’t Everything

Now you’ve got an idea of the type and size of rack or enclosure you’re looking for, but how can you tell which model is right? In the next installment, we’ll look at other considerations that should help you narrow your choices.