Color-coded PDUs: Why a little bit of color goes a long way in the data center

Color-coded PDUs: Why a little bit of color goes a long way in the data center

Manage your power infrastructure more effectively with color-coded PDUs.

There's a rainbow forming in the data center, and while you won't find a pot of gold at the end of it, you will find better power management infrastructure (and quite possibly a pot of cost savings).

We're talking about color-coded power distribution units (PDUs). They enhance data center managers' abilities to intuitively organize power infrastructure in these simple but powerful ways:     

Load balancing

Every data center has a cap on the amount of electricity their power infrastructure can feasibly support, and the goal is to strand as little of that potential capacity as possible. And yes, remote monitoring at the PDU level is invaluable to this endeavor since it can help you intelligently design your infrastructure based on power utilization trends.

However, 22 percent of data center outages result from human error. This could be something as simple as, say, plugging too many servers into the wrong PDU. When technicians add or remove equipment at the source, they also introduce the risk of error – whether that's from tripping on a cable (locking receptacles are clutch here) or literally getting your wires crossed and causing a power short by accidentally overloading a PDU. 

One simple way to solve this problem is to color-code PDUs based on their intended capacity. Just from looking, a technician can associate the power strip's color with its designated capacity, and match that against its current draw. These simple types of visual cues can help avoid silly but costly mistakes as new equipment is added or removed. 

... And they're nice to look at.... And they're nicer to look at.

A/B feed identification

Redundancy is everything in the data center, which is why each rack should have A and B utility feeds. This also means that every piece of equipment needs to be plugged into two different PDUs – one that's connected to the A feed, and one that's connected to the B feed.

Consequently, having two PDUs per rack can become a liability if each of those power strips are not intuitively labeled for an A or B feed. 

Facility managers can solve this problem by provisioning PDUs between feeds based on color. For example, orange PDUs can represent the A feed while blue PDUs can represent the B feed. Alternatively, lighter colors could represent the A feed while darker hues can represent the B feed. Setting it up this way enables you to designate specific colors to certain capacities while still having a feed identification system. The specifics of how you use the colors are really up to you. What's important, though, is that you have an easy way to distinguish between A and B feeds, and if possible, a system that shows you power capacity at a glance. 

Circuit identification

"Color-code individual receptacles based on their PDU circuit."

Finally, it's not just the metal chassis that can benefit from a color designation. On the power strip, each individual outlet is supported by a specific PDU circuit. This means that just as you need to evenly distribute load between PDUs, you may also need to evenly distribute load within the PDU. For instance, clustering too many blade servers or other high-draw pieces of equipment in the same circuit might cause it to trip, which would induce unplanned downtime.

One of the easiest ways to prevent this from happening is to first color-code the individual receptacles based on their PDU circuit. This ensures that its abundantly clear which outlet matches up to what circuit. Then, you can use color-coded power cables for your highest-draw equipment. This will make it easy to identify the high-energy consumers.

So, when a tech says, "There's already two red cables plugged into the purple circuit, but there isn't one plugged into the blue circuit," you'll know exactly what they mean.