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How to increase your storage energy efficiency

You can improve your storage energy efficiency by spinning down and powering off disk drives not in use, placing disk drives into a slower mode and using RAID levels and tiered storage.

What you will learn: Learn what you can do to reduce power consumption in your existing storage environment, as well as what to consider when purchasing products to increase energy efficiency.

Power and cooling issues have become (pun intended) a hot topic for IT-related equipment, especially video monitors, servers, networks and storage. The reasons for having an interest in power and cooling can be tied to green initiatives, budget concerns (rising energy prices) or simply to support growth for your applications and data requirements with an existing power and cooling capability.

Electrical power, along with heating, ventilation and air-conditioning (HVAC), have traditionally been an afterthought in the data center. Given the rise in energy prices, green and environmental awareness campaigns, and continued expansion of IT equipment to support more applications with larger data requirements, HVAC, power and floor space have taken on a new importance in many IT organizations.

Approaches to improve storage energy efficiency include:

  • Spinning down and powering off disk drives when not in use.
  • Continuing some use of magnetic tape for offline, long-term archive data.
  • Reducing power consumption by placing disk drives into a slower mode.
  • Using cache, RAM and flash or caching appliances, and solid state disk (SSD).
  • Consolidating to higher-capacity storage devices and storage systems.
  • Using various RAID levels and tiered storage to maximize resource usage.
  • Leveraging management tools and software to balance resource usage.
  • Implementing performance-efficient storage systems to support consolidation without hurting application performance or stability.
  • Another way to reduce power consumption is to address your data footprint. One approach is to refresh your technology with either a complete storage system replacement or by replacing the disk drives. In either case, you'll need to account for data movement and migration. For example, you could replace older disk drives of the same or larger capacity with newer generation drives that may have better performance and lower power consumption.

    For example, an early generation 73 GB (72 GB if you prefer) 15,000 rpm (15K) 2 Gbit Fibre Channel disk drive consumed about 18.74W (164.16kW annually) of power versus a current generation 15.5K (slightly faster) 4 Gbit Fibre Channel disk drive that consumes 15.24W of power. If you were to go to a higher capacity (say 146 GB, 15.5K) 4 Gbit Fibre Channel disk, you could double your capacity with a slight performance boost -- assuming that you're not doubling or aggregating the rate of I/Os to the disk via consolidation while reducing power from 18.74W to 17.44W. Keep in mind: When consolidating storage to larger capacity disk drives, you need to avoid aggravating performance bottlenecks.

    A sampling of what vendors are doing:

  • Brocade Communications Systems Inc. is demonstrating how its directors are more energy-efficiencient than one of its competitors, albeit consuming several watts per demo to do so.
  • EMC Corp. has released various articles and papers along with an energy calculator to support improving and maximizing power usage via consolidation, as well as leveraging VMware for server virtualization as a power saving approach.
  • Hewlett-Packard Co. (HP) is focusing on optimizing data center efficiency via improved cooling and assessment services to address immediate and near-term improvements levering its experience of consolidating and optimizing cooling in its own data centers.
  • IBM's "Big Green" initiative focuses on data center (internal and external) optimization for power and cooling, as well as technology improvements across servers and storage.
  • Sun Microsystems Inc. has partnered with Pacific Gas and Electric Co. (PG&E) to enable customers to qualify for energy rebates by reducing power consumption.
  • Other vendor approaches include 3PARdata Inc. buying carbon offset credits to compliment its thin provisioning or storage management virtualization capabilities. Other vendors including Copan Systems, Hitachi Global Storage Technologies (HGST) (disk drive manufacturer) and NEC Corp. have either implemented or made statements of direction around power management schemes ranging from intelligent multistep power management to simply power disk drives off to avoid power consumption.

    Additional things you can pursue to address cooling and power issues in your environment include:

  • Turning video monitors and lights off when not in use.
  • Following best practices, including covering unused floor openings in computer rooms, setting up cold and hot aisles where one aisle is cool (cooling area for intake) and another is hot (exhaust instead of cooling) to avoid hot-air intake by IT equipment, as well as reducing air blockage due to piles of cables under raised floor.
  • Understanding the facilities impact of deploying new technology, including floor weight loading, power requirements (connector type, kVa, phase), as well as cooling needs.
  • Explore raising temperatures in facilities, but stay within vendors' guidelines.
  • Get an energy or cooling assessment of your facilities and equipment.
  • Seek a balance of performance, availability, capacity and energy efficiencies to achieve effective results with regard to reducing your power and cooling needs.
  • Contrast the various approaches, and you be the judge as to what is applicable for your specific needs separating marketing "green wash" from approaches and solutions that can be deployed into your existing environment with realistic return on investment. Bottom line: There are many challenges and issues around power and cooling, and a diverse number of solutions and approaches. The best one for you will be the one that meets your specific requirements and may vary by location, application service level needs, as well as a ratio of servers to storage among other items.

    You can also learn more about power and cooling, and the electrical power generating and transmission industry andrelated topics at

    About the author: Greg Schulz is founder and senior analyst with the IT infrastructure analyst and consulting firm StorageIO Group. Greg is also the author and illustrator of "Resilient Storage Networks" (Elsevier) and has contributed material to "Storage" magazine and other TechTarget venues.

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