Early in my days as a Data Center manager I attended a series of talks focused on Data Center energy efficiency. The sessions covered everything from hardware chip design to application performance to physical infrastructure.
Even for a beginner, two things were immediately obvious. First, Data Centers consume more energy than other buildings – much more. Second, with so many different components drawing power there are a lot of opportunities to make a server environment more energy efficient.
One presenter, from a manufacturer of Data Center standby electrical systems, mentioned during his talk that electrical components operate more efficiently at higher loads. The closer they are to maximum capacity, the better they perform.
I thought about this for a while and at the conclusion of the session, asked: “If electrical systems operate more efficiently at higher loads, why do operators of Data Centers with redundant electrical infrastructure split the load evenly between the A and B sides? Why not put the entire load on side A and nothing on side B? Wouldn’t that be more energy efficient?”
To my surprise, the question stumped the presenter. Eventually, one of his co-workers in the audience stood up and said they had conducted experiments with that configuration and found that although it was more energy efficient, when a failure occurred on the A side and the full power load (in his words) “came crashing onto the B side,” the components sometimes failed. The redundant electrical infrastructure could reliably handle a sudden jump from 40 percent loaded to 80 percent, but not from zero to 80 percent.
Oh. Enter my third Data Center lesson for the day: energy efficiency is important, but ensuring availability is much more important.
Speaking of availability and Data Center power, this week’s question explores the use of rotary UPS systems that employ flywheel technology versus traditional battery UPS systems. See below for discussion of the pros and cons of each.
We’re formally opening a new Data Center today here at Cisco. In light of that, let’s forgo Data Center Deconstructed’s usual video Q&A and spend some time kicking the site’s proverbial tires.
Located in Allen, Texas, the new Data Center is a tier 3 facility with a 38,000 sq. ft. (3,530 sq. m.) hosting area and powered by redundant 10 MW feeds providing 5.25 MW of capacity for IT.
An overhead view of Cisco's new tier 3 Data Center in Allen, Texas.
I participated in several of the design meetings for the Data Center and am enthusiastic about a lot of the features that have been incorporated into its design. (No surprise, the facility uses all of the green strategies I discussed in Energy Efficiency Makes Two Kinds of Green and then some.) A few of my favorite features:
The active-active configuration. The Allen Data Center is linked to another tier 3 Data Center in Richardson, Texas, so each facility is a primary Data Center that also serves as a secondary facility for the other. Cisco calls the pair a Metro Virtual Data Center – I call it really hard to knock offline. (We like this model so much that we’re planning to build similar pairs in other theaters.)
The server cabinets. As shown in the image below, the Data Center’s cabinets have exhaust chimneys that allow hot air generated by hardware to flow into a plenum space and avoid mixing with incoming chilled air. This helps the cooling system operate more efficiently. (We used a similar design in our Richardson Data Center, too.)
A rotary UPS. If anything in a Data Center’s standby infrastructure is going to fail it’s the batteries, so I’m happy to dispense with a static UPS at this site. The rotary UPS contains a large, spinning flywheel and in the event of a utility power failure that kinetic energy will supply several seconds of ride-through power, long enough to transfer the Data Center’s electrical load to standby generators.
Enclosed cabinets with vertical exhaust ducts (chimneys) help isolate hot and cold airflow.
These are some of my favorites, but they’re just part of what this Data Center has to offer. For a deeper look, check out the interactive videos and detailed case study about the facility. Happy viewing!