Rack densities continue to increase as customers look to optimize data center utilization and reduce costs.

If you can go from 4 x 5 Kw racks to 1 x 17 Kw rack, why not?

The savings in real estate and infrastructure (racks, rack power strips, connectivity) are significant. Back of the envelope calculation gave me a savings of 55% going from 4 racks of 208V 30Amps (5Kw) to 1 rack of 208V 60Amp 3 phase (17 Kw) just in the rack and power strips costs. It doesn’t account for real estate, network ports saves, OpEx savings, etc.

However, with increased rack densities, there are challenges that need to be considered.

1) Strain on the existing power distribution infrastructure

This is the hardest to solve in legacy environments. But thoughtful retrofits can be possible. It is also an opportunity to look for providers who can offer high density installations.

2) Increased and/or more efficient cooling requirements

With higher density, cooling needs and efficiency also increase.

Containment solutions and precision cooling (in row or rear door cooling) can address the increased heat challenges.

3) Ensuring equipment in rack can support high temperatures

With increased density, the temperature inside the cabinet also increases. Therefore, components inside the rack need to be able to withstand the higher temperatures. From rack power strips to cables, verify what is the max temperature supported are.

On the rack power strips, I have seen maximum supported operating temperatures range from 45°C to 60°C (113°F to 140°F)

 

4) Weight concerns of the cabinet as well as the data center floor

For the cabinets, consider their static and dynamic load capacities. Some manufacturers have the same loading capacities for a 42U and 52U cabinet.

For the data center floor, how much weight can it withstand? Is the data center on ground floor or 2nd floor?

5) Balancing 3 phase power at the rack level

As densities increase, single phase power to the cabinet is not sufficient. Most likely 3 phase 30Amps, 50Amps or 60Amps will be needed. With 3 phase, balancing the IT load across the 3 phases can be a concern and a cabling challenge.

There are load balancing calculators which can help plan for the actual deployment. See example below, courtesy Raritan.

Also, some power strip manufacturers offer an “alternating phase” power strip solution. With this type of power strip, the outlets on the strip are laid out so that each consecutive outlet is tied to to a different phase, making balancing within the strip and cabling easier. See example below from Server Technology.

Alternating Phase PDU

High density rack deployments can provide significant savings in real estate and infrastructure costs.

Addressing the challenges above will help you reap the full benefits of high density rack deployments.


Original article first posted on LinkedIn on June 14, 2016 by Diana Li