What is server rack power density
server racks

What is server rack power density

Server rack power density is the amount of power the servers in a single cabinet can use. Older data centers support 3 to 5KW per rack, whereas more recent data centers that don’t use raised floors can achieve 30 to 50 KW per cabinets.

How is power density calculated

When looking into power density, you’ll see 2 metrics. Maximum power per rack and overall density.

The maximum power per rack is the total power a single cabinet can use, and overall density if the total IT power available averaged on the total white space.

In other words, a “30KW per cab” advertisement doesn’t mean anything if that load can’t be sustained over multiple cabinets. We’ve seen data centers deploy 15 KW cabs, and then be forced to limit all other cabinets in the row to 2 KW. Not very helpful for the high-density customer…

Why has average power density gone up?

The average power density in the retail colocation space has gone up. In the past, we’ve seen 3 KW on average, but in the last few years, that number has climbed to 5-7 KW.

Unlike what many think, the small 1-5 KW customers haven’t gone up in power density. Servers used by SMBs haven’t changed much, we would even say that they now have lower power consumption.

What explains the raise is that data center providers now have new cooling designs that allow customers to put more load in a single cabinet. Therefore, niche players like gaming or VFX clients have reduced their footprint by putting more servers in each cabinet.

Even if providers now charge per KW, some still charge for floor space. For that reason, it is to the client’s advantage to expand vertically rather than horizontally.

Vertical space

Another metric to consider is rack hight. Of course, you’ll be able to fit way more gear in a 52U rack compared to a 42U one. Although most retail racks are 42U, it’s not uncommon to see 44, 48, or 52U racks in high-density spaces.

Most downtown data centers don’t have the ceiling clearance to install tall racks, where as hyperscale data centers do. Anyways, not a single downtown data center has what is takes to properly sustain high-density across multiple cabinets.

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