Data center modernization projects are onerous and expensive. Using common sense approaches to airflow, equipment layout and overall design can increase efficiency, sometimes reduce the power bill and improve PUE. The key is to integrate various disciplines including power distribution, mechanical air flow and knowledge of the application requirements; to retrofit existing infrastructure rather than build out new data center capacity.
This was the message put forth to the Wikibon community on the April 6, 2010 Peer Incite Research Meeting. We were joined by Eugean Hacopians, Senior Systems Engineer at CalTech and Principal at Anre Technologies a data center consultancy.
Hacopians shared his experiences at CalTech and with other operations in which he's helped improve energy efficiency. A key message of the call was that while often vendors will try and sell you the latest and greatest equipment -touting improved efficiencies- it's best to understand your environment and consider practical ways to reduce energy consumption.
For example, Wikibon member Josh Krischer of Josh Krischer Associates shared some metrics about PUE. PUE stands for Power Usage Effectiveness. It is a ratio that measures the total power required for the facility divided by the power required for the IT equipment. A hypothetical value of 1.0 is perfection and unattainable. Krischer's estimates indicate that less than 10% of data centers worldwide have a PUE below 1.5 and on average he sees PUEs of between 2-3. This means that the total data center demand, on average, is 2-3X the demand for IT equipment.
The critical point for users is that replacing, for example, a CRAC unit and installing a more efficient unit, misses a large portion of the problem, namely the IT equipment. Rather if practitioners can find ways to lower the consumption of IT gear, it will have a ripple effect to infrastructure (i.e. power distribution and cooling).
Hacopians indicated that practitioners have three choices when they are out of power, cooling or space:
- Buy more dense equipment ("densify")
- Try to get more power
- Buy more CRAC units
In the case of CalTech, by following a straightforward recipe, the organization was able to completely shut off two of its nine CRAC units. Hacopians and Krischer recommended taking some practical measures - which won't always apply in all cases; including:
- Virtualize servers, storage and networking
- Use denser equipment
- Set up hot and cold aisles
- Avoid hot spots
- Improve air flow beneath raised floors
- Reduce the amount of air that must be cooled
- Plan your rack placement and avoid obstructions as you scale (e.g. columns)
The Human Touch
Hacopians stressed that most managers don't see the problem. Krischer shared some IBM statistics that indicate worldwide, less than 25% of data center managers have any control or authority over the power bill. Wikibon members in the U.S. indicate the figure is even lower (i.e. less than 10%).
Lack of metering and monitoring systems within the data center make tracking power consumption very difficult. Compounding the complexity of this problem is the fact that installing such systems is disruptive so it's always pushed to the back burner.
Hacopians recommends incentive systems that entice data center managers and employees to find ways to reduce energy consumption. In the case of CalTech, this led to simple and inexpensive fixes.
For example, CalTech's initiative to reduce energy consumption cost the organization $20,000 excluding staff time. The resulting savings amounted to around $2,000 per month according to Eugean. Perhaps more important, the organization has quadrupled its CPU power from 36 to 140 cores and double its storage capacity from 600TBs to 1200TBs-- while holding power consumption steady.
The bottom line is by thinking about what's possible before investing too heavily, and viewing the data center as a "living organism," CIO's can improve ROI, shorten breakeven periods and hold the power bill steady.
Action Item: Practitioners are often under the gun to address power pain points. CIO's should avoid the easy fix of installing more energy efficient CRAC and power distribution units without first going through the exercise of trying to reduce the energy consumed by IT equipment. Lowering the consumption of IT gear it will have positive ripple effects throughout the data center infrastructure.
Footnotes: Josh Krischer Data Center Efficiency Report