Using a Horizontal vs. a Vertical Rack PDU

RJ Tee
October 19, 2017

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While the use of vertical PDUs, or vertical rack power distribution units, has become nearly ubiquitous in today’s data center, they are not the only game in town.  Since we have been getting a lot of questions lately about Horizontal rack PDUs, we thought it would be useful to take moment to pause and reflect on our counterpart from the other axis.

Besides orientation, the most obvious difference between the two rack mount power strips is that of space – outlet space to be exact.  Since the typical horizontal PDU fills 1 to 2U gaps, the number of outlets available is limited to the width of the rack or the number of U spaces you are willing to part with. 

And sometimes, giving up rack space is about as appealing as anchovy-flavored toothpaste.

But more often, knowing how to optimize your rack space is a matter of understanding trade-offs and being able to balance your actual requirements with the configuration of your cabinet.  And, let’s face it:  we don’t all compute like Google and Apple.  So here are some key situations for you to think about going horizontal:

Do I distribute power from an in-rack UPS?  If your power loads are lower, or you protect your power through in-row UPS equipment, you may already be distributing from the U-space of the cabinet.  In this situation, many people find it makes the most sense to feed directly into a series of horizontal PDUs.

Do I have shallow IT gear?  Equipment such as switches and routers leave unused space at the back of the rack, and clever IT managers have been repurposing this area for cable management and power distribution.  Would you be surprised to learn that in the space of 2U, you have enough real estate for 26 outlets? 

Do I need to manage around airflow?  For some data center managers, the rear of the cabinet is off-limits, so to clear space for airflow, cable management must be as well-ordered as a circuit board.  In these situations, moving the rack PDU out of the vertical cabling space and into the horizontal space creates a place for cable managing.  It’s also out of the way of the server and storage appliances, and not in the discharge path.  

Server Technology is your power strategy expert. Head here for 1, 2, 3, and 4U Horizontal PDUs, and here for 0-U, or Vertical PDUS. We have solutions that allow you to configure in both the X-axis as well as the Y.

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