Green Storage – The Present and the Promising Future

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With rising concerns about energy costs and CO2 emissions, energy use in IT organizations is under growing scrutiny. According to a 2007 Gartner report, the information and communications technology (ICT) industries produce 2 percent of global CO2 emissions – on a par with the aviation industry!

Data storage, which has been seeing double-digit capacity growth for years, is an important factor in that equation. With such concerns in mind, three years ago The Green Grid – a consortium of IT vendors and end users – embarked on a high-profile quest to make IT more energy efficient. The results of that endeavor and of parallel efforts in government haven’t been spectacular, however, leaders and analysts say the groundwork is being laid for substantial long-term performance improvements, primarily through establishing what to measure and how.

In April, The Green Grid announced an agreement with the U.S. Department of Energy’s Save Now and Federal Energy Management Programs, the U.S. Environmental Protection Agency’s (EPA) ENERGY STAR Program, the European Union Code of Conduct, Japan’s Ministry of Economy, Trade and Industry’s (METI) Green IT Initiative, and Japan’s Green IT Promotion Council (GIPC) regarding “guiding principles of data center energy efficiency metrics.” All the parties have adopted the idea of Power Usage Effectiveness (PUE) as the preferred energy efficiency metric.

Rona Newmark, a member of The Green Grid and an executive at EMC (NYSE: EMC), said the focus on metrics is based on the simple notion that what you measure can be improved, and the specific concern that the overall effectiveness of power usage needs to be considered rather than looking at individual devices or systems. The result, said Newmark, has been a series of best practice recommendations developed by both vendors and user organizations. Where the best practices have been applied, he said, they have already driven 20-30 percent improvements in efficiency simply by not comingling hot and cold air, by using virtualization to improve utilization and by shutting down equipment that isn’t used regularly.

“A few years ago, if you talked about hot and cold aisles, most people thought in terms of the intensity of utilization rather than where air was flowing,” said Newmark. Now, in contrast, those new ways of thinking are “permeating the industry.” Although the focus of The Green Grid has been holistic, Newmark said some specific attention has been given to storage, too.

“One of the fundamental understandings that has come out of this process is the realization that the power draw of disk drives varies proportionally with the rotations per minute, not with disk capacity,” said Newmark. Therefore, two drives with the same spindle speed will use nearly the same amount of energy, even if one is of considerably higher capacity.

“The energy used in seeking and reading or writing is marginal in comparison to the energy used for rotation,” she added. Thus, the increased use of 10,000 RPM and 7,200 RPM SATA drives has not only lowered the cost of purchased storage capacity, it has lowered energy use as well. The increased use of solid state disk (SSD) in place of Fibre Channel drives has also resulted in reduced energy consumption, she said.

“There haven’t been any big banners advertising this, but those fundamental shifts are playing an important role in cutting energy use,” she said.

In addition, architectures such as MAID (massive array of idle disks) and other systems in which some drives are “spun down” when not in use also offer potential savings. “Though that clearly wouldn’t work for applications such as online transaction processing (OLTP) and other demanding uses,” said Newmark. Likewise, tape, which usually has low energy usage, is also a potential component in efforts to reduce energy consumption.

Greg Schulz, founder and analyst at the StorageIO Group/a> and an activist on green issues with the Storage Networking Industry Association (SNIA) even before the Green Grid was announced, said there is still a common myth that MAID is the only green solution out there. But, in fact, there are many other ways to avoid or reduce power consumption.

Spinning down disks can sometimes lead to increased energy use due to decreased throughput. “It is like having a fuel efficient car stuck idling in traffic,” Schulz said. In some cases, it may be possible to improve PUE by adding faster drives or processors. In a similar way, some vendors are looking at smarter power management, sometimes called intelligent power management (IPM), which tends to consider operational effectiveness along with power usage.

While saluting the work of The Green Grid on PUE and standards, Enterprise Strategy Group analyst Mark Peters said their role remains primarily that of a cheerleader bringing attention to an important issue. For Peters, the smart money is on solid state. “This is not because SSD is so efficient as the SSD manufacturers would have you believe, but because it enables really effective automated tiering,” he said. Peters stressed that it is important to make a distinction between storing and using data. With SSD, you can put IO functions where they belong, in the fastest medium. SSD will handle IO and “big fat disks” will store things, according to Peters.

To be sure, tiering has been around for a while, but the difference now is automation, which makes it much more practical, he said. “This is something that large and small vendors are jumping on, in fact there has already been a flurry of announcements in this area, such as FAST (fully automated storage tiering) from EMC.”

“I believe we are in a hockey stick situation with this, where the adoption of tiered storage and SSD is about to take off. It is coming fast and you won’t have a choice because it will become universal,” Peters said.

And, he noted, when tiering becomes a bigger factor in storage management, tape will probably still play a role – perhaps even a growing role. “Unless someone comes up with the ability to store data in a sugar cube, tape will remain the cheapest, high capacity medium with the greenest footprint.”

Alan R. Earls is a writer specializing in business and technology. He is based in the Boston area.

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