The Heat is On: Storage and Energy
By Fred Moore, President, Horison Information Strategies

Electricity is mission-critical to most every business in the modern world and without electricity, there is no IT industry. The faster micro-processors become and the faster a disk spins, the more energy it takes to spin them and the more cooling they require - and the same occurs for tape drives and other motor-powered devices. Today, servers account for approximately 40% of the data center's overall power consumption, and storage takes just over 35% on average.

Clearly, a huge financial opportunity exists to improve storage efficiency and reduce energy consumption. In a data center user group survey from the Liebert Customer Survey Enterprise Storage Forum, "33% of respondents expect to run out of power and cooling capacity by the end of 2007, and 96% stated they would be out of capacity by 2011." Given the trends of rising global energy prices and projected digital data growth at ~40% annually for the foreseeable future, this is not only a matter of addressing the IT budget, but it also becomes the challenge of diminishing availability of energy resources. A study by The Uptime Institute of 19 computer rooms with more than 200,000 square feet of floor space found that they had 2.6 times more cooling than required, but wasted more than 60% of the capacity because of poorly designed airflow and layouts. Simply put, data centers are rapidly putting serious pressure on power and cooling capacity for a variety of reasons.

IT Technologies are Heavy Consumers
It is estimated that as much as 30%  or more of all electricity consumed in the US by the year 2010 will be by information technologies and the increasing number of personal digital appliances. Data centers often use well over 100 watts per square foot, more than 10 times that of the average household. The cost of energy is now increasing at 20% - 30%  annually in many geographic locations, making energy consumption one of the largest considerations in the TCO (total cost of ownership) of computing equipment and when building a new data center.

Servers
Servers are large consumers of electricity. Before the year 2000, servers drew about 50 watts of electricity - now they use up to 250 watts, and there are more of them. Blade server technology best illustrates this point. As many as 60 servers can be placed in a standard height 42U (U=1.75 inches) rack. The typical power demand (power and cooling) for this configuration is over 4,000 watts.

The trend toward high-density packaging continues, without enough attention being focused on energy consumption. Suppliers are using packaging schemes that tightly pack more boxes into more racks in the data center, increasing heat density and cooling requirements exponentially. These technologies all use fans, but fans just move heat, they don't remove heat.

Air conditioners normally are used to remove heat, but they increase overall IT costs significantly. Chilled water and liquid refrigerant solutions first appeared with S/370- model 168 mainframe computers in the 1970s, and later gave way to air-cooled systems as businesses became concerned about leaks, moisture and plumbing issues. Nonetheless, expect to see liquid cooling regain momentum, since it is more efficient at removing heat than air cooling. Spot liquid cooling solutions are expected to appear first, as they can provide liquid cooling for specific products such as server racks, blades and dense disk arrays.

Currently in the US, more than 50% of the annual 4 trillion kilowatt hours of electrical power is consumed by motors, which includes those used in disk and tape drives. The efficiency of small motors can be less than 50%. Motor efficiency increases to over 90% as motor size increases, but larger motors consume more energy, too.

Storage
For storage systems, fewer devices mean less energy consumption. Poor storage management practices, such as keeping disks spinning 24 hours per day with mostly low-activity data, unnecessarily increases power and cooling expense compared to alternative storage solutions that only use energy when the data is accessed. Storage utilization figures differ by operating system and by the type of storage device. Mainframe systems have higher allocation and utilization levels as a result of the powerful suite of proven storage and data management tools. Non-mainframe systems don't have a comparable suite of mainframe-class tools, so that delivering higher levels of utilization is significantly more labor-intensive and difficult to achieve on these systems.

Energy Savings Through Optimization
For non-mainframe disk systems, the allocated/used levels for a physical disk average about 40%. The mainframe disk allocated/used levels are typically double that of non-mainframe systems and average about 80%. The challenges for disk users are growing as the capacity of new disk drives is increasing much faster than drive performance. As a result of this imbalance, storage administrators often allocate less space in order to maintain acceptable performance levels, thus requiring more drives. As utilization levels drop, more devices are needed, increasing total disk costs and energy expense. Improving utilization by improving storage management, along with the growing success of storage virtualization capabilities, can reduce the device population and improve efficiency.

Using 7,200 rpm or 10,000 rpm disks versus 15,000 rpm drives helps, as the slower spin rates obviously use less energy. What about the disk form factor? Smaller form factors such as 2.5-inch disk drives require about 5 volts vs. 12 volts for today's de-facto standard 3.5-inch form factor. Small form factor drives tend to have smaller capacities. Controllers and other components are part of the overall power consumption calculation.

Magnetic tape cartridge utilization also varies by operating system and by tape architecture. For mainframe systems, tape cartridge allocated/used levels were often 25%  or less before the arrival of the first virtual tape library systems in 1997. Integrated virtual tape libraries (a disk array and a tape library) enable intelligent stacking of multiple virtual tape volumes on a single tape cartridge. This has proven to be highly effective in driving up cartridge utilization and driving down the number of drives, libraries and total media count, and thus reducing energy expenses. Virtual tape library implementations commonly experience allocated/used levels of 80%  or more for tape cartridges. Since over 70% of digital data is moderate to low activity, it makes economic sense to store this data on energy efficient technologies such as MAID (Massive Arrays of Inactive Disks), the new hybrid removable disks and automated tape libraries. Managing an effective tiered storage hierarchy can significantly reduce energy consumption.

Energy Metrics and Tools Emerge
Does your business monitor and manage power consumption? Power management software is emerging as the next IT management tool bridging the gap between IT and facilities management. Many new energy management tools are Web-based to enable quick implementation. Some tools allow management and monitoring of UPS, while some measure and report power consumption and air temperatures across blade servers while posting alerts. Others report on electricity usage, including who is consuming the energy, percentage of power capacity consumed, quality of input power, related environmental data and cooling systems status. These solutions come from a variety of vendors and are usually vendor specific. Typical of most software products, the unending issues of proprietary versus open remain, as not all energy management tools work with all products.

Storage vendors are moving toward power density and storage density as common metrics for their competitive marketing messaging regarding power consumption. These metrics originally were used with the advent of automated tape libraries, but have regained momentum in recent months as the energy issues are mounting. Power density is the total capacity divided by the power consumption in Kilowatts. The higher the power density the better, as it means the more each KW can support. Storage density is emerging and is the ratio of terabytes per square foot. Here, the higher the storage density, the less data center floor space is required and less cooling.

Conclusion
Heat waves and the threat of energy loss expose areas of risk to the IT community that were taken lightly in years past. With reserve electric capacity declining in the U.S., power availability issues will likely continue to mount. Unlike the storage industry where the suppliers strive for improved efficiencies and to decrease the price per unit (GB or TB) of storage annually, the energy industry pricing model consistently increases the price per unit (KWH) annually, placing increasing pressure on cost and price reduction, offsetting any financial savings from reduced consumption. At the current pace, the cost of energy has become a huge concern and will surpass the entire costs of the computer systems for many businesses in a few years (some are approaching that point already).

The impending energy crisis will encourage aggressive use of environmentally conservative or green storage solutions, such as removable media and powered-down drives for less-active data. Tiered storage implementations will experience even more momentum as this process unfolds. Developing an energy strategy is becoming mandatory, and several businesses have created a new position of "Energy Systems Manager" to ensure that floor layouts and airflow are properly designed and adapt to ongoing equipment changes in the data center. Where are you with your energy strategy? Remember - without electricity, there is no IT industry.

Sources:
http://www.solarenergy.org/resources/energyfacts.html
http://www.facts-about-solar-energy.com/facts-about-solar-energy.html
Storage Spectrum, 2007. Horison Information Strategies. Fred Moore
The Fund for Renewable Energy Everywhere
The Official Earth Day Guide to Planet Repair
The Worldwatch Institute
U.S. Department of Energy

About the Author
In 1998, Fred Moore founded Horison Information Strategies, an information strategies consulting firm in Boulder, Colorado that specializes in marketing strategy, industry analysis and business development for the IT industry.