"No one technology is a silver bullet," said Greg Schulz, founder and senior analyst at StorageIO in Stillwater, Minn., and author of The Green and Virtual Data Center. "If you focus just on spinning drives down, or just on dedupe, or just on thin provisioning, you have a missed opportunity. You have to look at the overall environment and use different tools and techniques for different areas. Avoid putting blinders on."
IT shops with performance-intensive environments need to focus on more IOPS or transactions per watt of energy, while those saddled with large amounts of inactive data should concentrate on increasing the capacity per watt of energy and reducing the data footprint, Schulz advised.
"You can either avoid energy, or use it more efficiently and more effectively," Schulz said.
Energy conservation projects: Where to start
In the context of an organization's overall IT equipment, storage may represent no more than 15% to 30% of the energy consumption, so it might not be the first place to start energy conservation projects, wrote David Vellante, co-founder of The Wikibon Project, in an email. The process could start with intelligently laying out the data center and setting up hot/cold aisles and smart airflow, he noted.
"One of the biggest mistakes made in IT shops is they focus first on air conditioning and power distribution," which service the IT equipment but provide no direct business value, Vellante wrote. "Make sure you target the IT equipment first, because if you can reduce that load, you automatically get a double effect," also reducing the power and cooling requirements.
Brian Garrett, vice president of the Enterprise Strategy Group Lab in Milford, Mass., advises IT shops to make energy efficiency one of their storage purchasing criteria and to ask vendors to calculate the power consumption of the storage systems they're buying, since it may not be as straightforward as they might think.
Energy Star-qualified data center storage products
Selecting data storage equipment may become easier once the U.S. Environmental Protection Agency (EPA) makes available a list of Energy Star-qualified data center storage products, similar to the ones that help consumers evaluate refrigerators, air conditioners and other appliances.
To produce the Energy Star storage list, the EPA is in the process of collecting data from storage manufacturers on the amount of energy a particular type of product uses; after analyzing the data, it will set the energy usage levels a product must meet to gain recognition as the most efficient in the market.
"We hope to get [the list of Energy Star storage products] out by the end of this year or early next year," said Una Song, a program manager for the Energy Star initiative at the EPA. "It's all subject to the data that we receive and the number of drafts we need to do with the specifications."
Song added that the EPA is considering the reporting of environmental features, such as thermal information, in the Energy Star storage list to help IT shops optimize the heating and cooling of their data centers.
"That's a little different than what we do with appliances, but in general, the [Energy Star storage] label will mean the same in the data center as it does in a consumer's kitchen," Song said. She noted that the specification development process is open to anyone, and email feedback is welcome at email@example.com.
Power savings through storage efficiency technologies
While Energy Star ratings may prove helpful, they're unlikely to be the make-or-break factor in the data storage equipment purchase process, since IT shops often tend to rank criteria other than power consumption higher on their priority lists.
Concord, Mass.-based Welch's, for instance, placed energy efficiency in the lower half of its wish list when evaluating storage systems from EMC Corp., IBM and NetApp Inc. to replace a pair of IBM DS6800 arrays, according to Mukesh Sharma, a senior IT manager at the company.
In the end, Welch's chose IBM's XIV Storage System without comparing it to the EMC and NetApp products on the basis of energy efficiency. Sharma said higher-priority items such as scalability, resiliency, performance and features such as mirroring, snapshots and thin provisioning had already swayed his IT team.
But, if an IT shop should ask, each of the vendors is at the ready with its pitch for energy efficiency. EMC, for instance, touts features such as virtual provisioning, disk spin-down, high-performance flash drives, large-capacity SATA disks, data deduplication and adaptive cooling.
More recently, EMC began promoting its Fully Automated Storage Tiering (FAST), which can steer data to enterprise solid-state flash or SATA drives based on performance requirements. EMC claims FAST can help users to lower system costs by 20% and operating costs, including energy consumption, by as much as 43%.
NetApp counters that its customers can reduce data storage, power and cooling requirements by at least 50% if they use each of the following nine technologies in its products: RAID-Double Parity (RAID-DP), snapshots, thin provisioning, SATA drives, data deduplication, Flash Cache, SnapMirror, SnapVault and FlexClone.
Larry Freeman, a senior marketing manager of storage efficiency solutions at NetApp, noted in an email that the traditional line of thinking was: "What is the power draw of my disk drives, fans and power supplies, and how can my vendor make those components more efficient?" He said NetApp now encourages customers to ask: "How can I reduce the number of storage arrays in my data center and the number of disk drives in each storage array?"
IBM's energy-efficiency pitch with XIV Storage System centers on its large-capacity, enterprise-class SATA disks that consume less power than Fibre Channel disks. The company also claims XIV's grid design -- with massively parallel I/O operations and distributed cache memory, automatic striping of data across all modules and disks, and thin provisioning -- factors into the energy-efficiency equation.
Welch's participates in a "power-saving challenge" with its local power provider, but the company doesn't break down usage by department, so the IT staff isn't sure if the XIV Storage System has actually lowered consumption. Welch's Sharma knows only that the single-rack XIV at the main data center did not require the addition of any power or cooling after the removal of the two DS6800s with their 15,000 rpm Fibre Channel disks.
The 15-module XIV that Welch's deployed last year in Concord has 180 disks and 79 TB of usable space. The company uses 20 TB of the 27 TB it licensed, with plans to license another 20 TB during its next fiscal year.
"We have the growth built within that rack itself without any additional footprint. That was a significant point," said Sharma, noting the limited space in the data center. "At the same time, we don't want to put a lot of load on the same system and see performance issues. The architecture of the XIV was the selling point for me. There's no bottleneck on one disk."
The grid-based system spreads the data across all of the 180 disk spindles, even though Welch's isn't running at full capacity, he said. Welch's is also in the process of implementing a smaller, six-module XIV Storage System at its Billerica, Mass., data center that uses 12 TB of the 27 TB available on 72 disks.
To try to contain its data storage growth, Welch's makes heavy use of space-saving snapshots to eliminate the need for full-system copies whenever the company needs to back up or create a nonproduction, development or test environment. It also uses thin provisioning in its development environment.
"I hope that translates back to energy savings, because I'm not using all that storage," Sharma said. He added that he also expects to take advantage of disk spin-down capabilities and purchase tools to measure energy and cooling consumption.
Worrying about overall efficiency, rather than focusing exclusively on energy, does tend to have positive ripple effects on power and cooling, according to Wikibon's Vellante.
"Balance is the key," Vellante wrote. "Balance cost, business value and operational risk."
This was first published in July 2010