The big wins for data center efficiency tend to come at large so-called “scale out” sites where a lot of kit is aggregated. The ones with the most freedom to design for efficiency are the giants whose whole data center serves one user - or even one task.
These are the guys whose power usage effectiveness (PUE) ever more closely approaches the magic goal of 1.0. Facebook is justly proud of the live feed of its Prineville data center, which as I write shows a PUE of 1.07, helped by a chilly outside temperature fluctuating from 30F to 46F (roughly -1C to 8C).
That’s all very well, but colocation providers have a tougher time. They have large halls, but the space inside is rented out by the rack, and they have little control over what is in those racks.
Colo’s cool conundrum
Even though IT hardware is getting more reliable, colo providers don’t get to push the air intake temperature higher (which can make your PUE way better) because the kit in the racks doesn’t belong to them and they can’t take even the slightest risks with it.
Some shared spaces have agreements where different customers get different reliability and power density - for instance in the UK, Infinity’s deal with the UK’s Janet academic network. The main benefit of such deals deliver is the massive efficiency improvements over the separate data centers that get aggregated into one space. The PUE is normally impressive, but somewhat short of what a Facebook can deliver, because of the constraints.
Despite this colocation providers have a strong incentive to improve. In the UK, a Climate Change Agreement (CCA) gives them a tax break on the basis that their PUE will improve over time. This cut in tax is for colocation and cloud providers only, not in-house data centers, and so far some 100 companies have signed up to it.
Live PUE from a colo
Although colocation efficiency is therefore coming under the spotlight, I’m only aware of one colo provider publishing a live feed to its PUE - Custodian Data Centers in Kent, UK. The site occupies a former TV studio which was once the home of the Muppets, and currently has a PUE under 1.2 (the picture shows Custodian moving in)
If you know of others with live PUE feeds, get in touch.
“The feed has had its ups and downs reflecting maintenance windows, changes to site configurations and seasonal weather patterns,” says Robert Williams, technical director at Custodian. “Yet this warts and all approach has left us stronger and more informed.”
Williams explains on the Custodian site that the Tier IV facility can’t get much closer to 1.0, since it has to have a dual path power supply, with twice the number of uninterruptible power supplies (UPSs) on standby.
He also reveals another benefit of the live PUE feed. It’s based on a lot of sensors, which his staff use to tune the data center. For instance, the air conditioning in the UPS room is set to provide the right amount of cooling and no lower.
Once again, information is power - and colos benefit too.
A version of this article appeared on Green Data Center News.