SNIA Tackles Green Hype in Storage

As enterprises pay more attention to energy usage in the data center, storage vendors are touting their "green" credentials and making claims that their systems are more energy efficient than those of competitors. But buyers of storage systems have a hard time comparing those claims since there are few concrete standards for measuring and comparing energy usage for complicated technologies like storage. The Storage Networking Industry Association (SNIA) , which has been working to improve energy efficiency in storage and promote conservation, this week introduced its Green Storage Power Measurement Specifications, the latest step in its effort to level the playing field when it comes to green claims.

The trade group, which includes most major storage vendors, issued for public review and comment two new elements of its Green Storage Initiative. They include a taxonomy that places various storage technologies and systems in categories to permit comparisons between systems and a method for measuring the amount of power a system consumes when idle. More than 25 vendors were involved in developing the taxonomy and idle power measurement approach.

SNIA is devoting considerable effort to developing industry-wide specifications for measuring and comparing energy usage of storage systems because of the increasing attention being paid to the amount of electricity that goes into powering and cooling data centers and IT systems in general. Industry analysts estimate that storage systems use 13 percent of the energy consumed in a typical data center, and that the percentage used by storage could grow as companies continue to buy and deploy more capacity.

"And every watt you burn [to power systems] you burn another watt in cooling," says Al Thomason, vice chairman of SNIA's Green Storage Initiative and a storage portfolio manager at IBM Corp. (NYSE: IBM). "I've seen some estimates that storage consumes up to 30 percent of the power in a data center."

The SNIA taxonomy groups storage technologies and systems into five main segments, ranging from small office, home office, and consumer storage systems all the way up to enterprise mainframe systems. It sets criteria for what kinds of devices and systems fit into each category, making distinctions among online, near-online storage, removable media libraries, virtual media libraries, infrastructure appliances, and infrastructure interconnect systems.For example, midrange enterprise systems are described as "SAN or NAS connected storage which delivers a balance of performance and features. Offers higher level of management as well as scalability and reliability capabilities." The taxonomy then uses the number of devices and drives a system supports or uses to place them into various boxes to permit fair comparisons of systems.

"We wanted to cover all of the technologies contained in storage and build something that would scale for the future. It took a long time to resolve," says Thomason. The goal was to develop a system that would stop vendors from comparing a tape system to a disk system or a midrange system to an enterprise system, yet would be able to incorporate new technologies like appliances, virtualization, and data compression.

"We have to recognize the different design points of each category of equipment. An enterprise system does consume more power than a midrange system, but it delivers more power and features. This will help to ensure that people are comparing apples to apples."

The Idle Power Measurement methodology, which makes use of the taxonomy, is the first measurement technology the group has issued. It has two test phases, one that measures a system's power use in a "pre-conditioning phase," which is when all elements are fully operational and the system stands ready to process I/O requests, and an idle phase, which is when a device or system can process I/O requests within a maximum access time requirement as specified in the taxonomy. For disk-based storage, the idle measure is captured over a 24-hour period. SNIA will be working on active power measurement throughout this year.

"We made a distinction between online and near online systems like MAID [massive arrays of idle disks]. By our standard, online systems have a maximum of 80 milliseconds to access data," Thomason says.In developing the specs, the group found it had to take a wide variety of factors into consideration. One key element is system housekeeping, when the device or system checks the condition of disk drives or moves data for load balancing or performs other functions at different times. To balance out the proprietary housekeeping systems that different vendors use, the specs require that measurement of energy usage for online storage be conducted over a 24-hour period.

SNIA hopes its specs will become a standard yardstick that will let buyers make comparisons between products and a tool for optimizing energy usage in data centers. It also can be used by vendors to optimize systems and better understand the energy usage impact of adding new features and capabilities. It may also end up being used by regulatory agencies as they put energy usage goals and guidelines in place.

These are the latest elements in SNIA's comprehensive Green Storage Initiative, which includes educational tutorials, whitepapers, alliances with other Green groups and organizations, and industry "Unplugged Fests," where vendors bring in their equipment, perform measurements, and share ideas and technical approaches.

"Customers don't want to hear a lot of 'green washing' or hype. They want to know what vendors can do today from a green perspective," says Thomason. "Customers know that there are significant savings to be obtained, and they are looking for true value. We believe these specs can help to provide real value for all participants."