Rack Fans & Cooling

Let's Talk About Data Center Cooling

When it comes to data centers and server rooms, temperature management is one of the most important challenges that must be tackled. The simple fact is that heat isn't very good for electronics, and conversely, servers generate a lot of heat. The more servers you pack into a finite space, the more heat you're going to generate. Overheating can lead to damaged components, not to mention downtime, both of which can have dire consequences. There are many ways to manage heat and introduce cooling into a server environment, from air conditioning to layout design. We'll take a look at them, but first let's go into a little history.

In the Beginning...

One of the early methods of cooling data centers was the "chaos" air distribution method…catchy name, right? In this method, you had computer room air conditioning (CRAC) units around the perimeter of the data center that would supply lots and lots of cold air into the room, which would cool the equipment and push hot air toward the return ducts to be cooled by the CRACs. This wasn't ideal for a lot of reasons. The cool air didn't always get where it was most needed, and the hot air didn't always make it to the return ducts, instead getting into server air intakes and making equipment dangerously hot. Additionally, in an effort to deliver more cool air, the CRACs would pump out air too quickly for the server intakes to draw it in, so it would end up funneled right back into the return ducts before it even had a chance to cool the equipment. Obviously, this wasn't sustainable, so eventually a layout was developed that helped deal with these issues.

You're Hot, Then You're Cold...

The first steps you can take to manage your airflow have to do with how your area is set up. The development of "Hot aisle/cold aisle" helped solve a lot of the problems with the "chaos" method, and has become the go-to layout for servers. Basically, you set up your equipment so that the intakes (for cold air) are facing toward each other and the exhausts (for hot air) face each other (or the wall AC units). The area with exhausts facing become "hot aisles" while those with intakes facing each other are the "cold aisles". Typically, air from the hot aisle is captured by CRAC units, cooled, and then fed into the cold aisle via perforated raised flooring systems...

It's Gettin' Hot in Here...

There's still a problem with hot aisle/cold aisle, however: hot air and cold air can still meander into undesired areas. That's why, after your aisles are set up in this configuration, you'll need to institute a containment method to keep the cold air away from the hot air and vice versa. Think of it like Ghostbusters, only instead of trying to keep a bunch of spooky specters from running amok in New York City, you're trying to keep the hot air from invading your cool spaces and ruining its chill vibe. There are many items available to aid in managing the airflow in your server environment.

• Air dam skirt that attach via magnets or Velcro to the bottom or top of an enclosure help to block air that might pass underneath or over the top of a server cabinet.
• Blanking panels can help to keep air from traveling through unused rack space. They can be purchased in single 1U units, or in sheets to take up larger area.
• Foam air dams or brush grommets can help create a snug fit barrier around any cable bundles or pipes that may pass between hot and cold areas, which mitigates the amount of heat and cold that can escape between the aisles.
• Split rear doors can also help redirect hot air upwards and away from cold aisles.

Think Beyond the CRAC

While CRAC units are still used to cool data centers, there are many supplemental cooling products that complement a CRAC unit as well. Portable air conditioning units, such as the ClimateCab AC units by Black Box, can attach directly to racks or enclosures to cool components, rather than the area around them. There are also a wide variety of fan cooling options available. Fans can help keep individual components cool during operation, and are an option for rack set ups in confined spaces, where larger AC units may not be needed or practical. They typically take up as little as 1U of rack space and can install directly into your rack or enclosure.

Data Center Feng Shui

A final word on data center design: whenever possible, it's ideal to design the room around the equipment, not vice versa. In practicality, of course, this isn't always possible. However, the traditional method of shoving as much IT and cooling equipment in a room as is physically possible has some obvious flaws that could cause serious issues down the road. We can't all be Google and Facebook, obviously, designing data centers the size of giant warehouses to fit our server demands. However, it's still a good idea not to overload a space with more equipment than it can handle. You'll end up paying in the long run, so be sure that your cooling power is able to meet the demands of your heat generation, in a way that's efficient enough not to break your budget.