博客

Data Center Cabinet Load Balancing:  there’s a less complicated way.

Posted on March 28, 2017 by Gento  |  Comment (0)

Rack PDUs in a Server Rack

Why do we load balance?

Without going into the complicated math, suffice it to say that load balancing in a 3 phase system is desirable.  The more unbalanced a system the more problems it creates.  UPS life, for one, can be affected by unbalanced systems.  Although one circuit (server cabinet) being out of balance won’t have much effect, if many or all circuits on a panel are out of balance, the main circuit supplying the breaker panel will be out of balance and this can ruin your upstream UPS.  There are also efficiency issues with unbalanced loads.

How is load balancing currently accomplished in a rack cabinet?

To balance a load in a cabinet, the loads of the equipment power supplies are spread across the 3 phases – L1/L2, L2/L3, L3/L1.  This is done by plugging the first server (or switch/router) in an outlet wired on L1/L2, the next server on L2/L3, the next on L3/L1, then start over.  The goal is to get an equal number of devices/loads on all 3 phases – or as close as possible. 

This approach can quickly turn into a cabling nightmare. Most rack PDUs are linear in their phase layout of outlets – there are only three banks of outlets, one for each phase.  For example, on a 36 outlet PDU, outlets 1 through 12 will be on L1/L2, 13 through 24 on L2/L3, and 25 through 36 on L3/L1.  If you use the above method of balancing, and start racking the devices at the bottom U position, the third device you plug in will need to reach the top third of the PDU and the last device may have to reach back to the bottom of the PDU.  In other words, a lot of crisscrossed cabling.

How do Raritan’s balance the cable and load balancing challenge?

In certain Raritan PX three-phase models the architecture gets around the cabling issue by staggering the grouping of outlets - there are at least 6 banks of outlets.  For example, outlets 1 through 6 are on L1/L2, 7 through 12 on L2/L3, 13 through 18 on L3/L1, but then we start over at L1/L2 for outlets 19 through 24. (See Illustration below)

This intelligently engineered architecture results in more reliability and easier execution.  The devices towards the top of the cabinet don’t need to be plugged in to the bottom of the PDU and devices at the bottom don’t need to be plugged in to the top.

Raritan V2 Architecture Diagram

The Result

By using Raritan’s alternate circuit phase sequencing, you will be able to more easily and efficiently balance your cabinet load. The approach simplifies deployment of IT devices and balances the three lines to get the most power headroom.  Also, tracing a power cord to a device becomes much easier and thus, unplugging the wrong device during maintenance or replacement will be less likely. Resulting in less downtime… always a good thing!




Other Blog Posts

KVM Switches: What You Need to Know
Posted on January 18, 2018
Micro Data Center Environments
Posted on January 18, 2018
Data Center Infrastructure in a Software-Defined and Virtualized World
Posted on December 24, 2017
4 Reasons Why Xerus Technology Platform APIs Make Your Data Center Management Easier
Posted on December 24, 2017
Data Center Physical Security at the Rack
Posted on December 24, 2017

View all Blog Posts

訂閱

近期活動

Cisco Live 2017
March 7 – 10, 2017  •  Melbourne, Australia
Data Centre World Hong Kong
May 24 – 25, 2017  •  Hong Kong
DatacenterDynamics Australia
Jun 27, 2017  •  Sydney
DatacenterDynamics China
Jun 15, 2017  •  Shanghai
Technology in Government
August 1 – 2, 2017  •  Canberra, Australia

View all Events

Raritan最新新聞

Packet, Myriad Supply, Raritan, and Data Center Knowledge to Participate in ‘Managing the Edge’ Webinar
Posted on November 12, 2017
Raritan Employees Support Green Community Projects
Posted on November 8, 2017
Data Center of 2025 — What to Expect
Posted on October 30, 2017
Congratulations to LinkedIn’s Hillsboro, Oregon, Data Center
Posted on July 30, 2017
Raritan Intelligent Infrastructure Solutions Bolster Data Center Performance
Posted on June 26, 2017

View all news