Data storage technology brings data center power consumption benefits

As data center power consumption rises, some IT shops find unexpected benefits in more efficient data storage technology. Find out how two firms saved money on power.

In the drive to make IT infrastructure greener, data storage technology is becoming a key piece of the puzzle. Historically, storage has been a "dirty" technology, in terms of data center power consumption. The resources used to store large amounts of data require inordinate amounts of power and rack space, representing a significant overhead in the data centre. Traditionally, enterprise users have relied on relatively large 3.5-inch hard disk drives, which are kept constantly spinning at very high speeds to increase performance. But spinning heavy pieces of metal takes a relatively large amount of power.

The management of storage resources has also contributed to the problem. Companies have traditionally allocated physical chunks of storage to particular departments, servers or applications. This has led to overprovisioning of hard drive space, wasting energy as the disks spin with allocated but unused space.

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A variety of techniques have emerged to help reduce the power and space overhead in storage infrastructures. Slimming down disks to 2.5 inches, for example, makes them easier to spin. Seagate has done research suggesting a 45% to 50% reduction in power usage with 2.5-inch disks vs. 3.5-inch disks. Some companies have experimented with large numbers of hard drives, which are spun down either at regular intervals or when not in use and spun up again when needed, thus saving power. However, spinning down drives is only one option.There are systems, like Nexsan's, that have several settings that trade off performance for power savings. Still other IT shops are looking at the deployment of solid-state drives (SSDs), which do away with mechanical parts altogether, minimising the power overhead involved in data storage and transfer. Other green storage tactics include thin provisioning, tiered storage and data deduplication. Finally, virtualization technology makes hard drive provisioning more efficient, allocating storage capacity exactly where it is needed without wasting it.

According to a recent green data storage technology survey by, two-thirds of respondents said they would pay extra for a green product, indicating that green credentials were a primary issue. However, not everyone agrees.

Virtualized SAN increases performances, reduces footprint: Intercept IT 

"Green is a by-product of a project. No one will go green just for the sake of going green, because there is a cost associated with it," said Gary Collins, CIO of Intercept IT, a UK-based company that hosts cloud-based services for customers and provides consulting services in cloud-based infrastructure design. Collins' team recently moved to a thin provisioning system that he said has enabled the company to save approximately 70% of its storage-based power requirements.

Collins migrated to a virtualized SAN from 3PAR capable of thin provisioning, after his four installed SAN arrays -- three at a colocated Milton-Keynes data centre and one at a backup disaster recovery centre -- started to reach the end of their useful lives. "The whole thing was a mess. We were getting some bad performance from our storage architecture," he said.

After procuring the 3PAR system, which was the only offering that could guarantee the company the 20,000 IOPS it needed with its £250,000 budget, performance increased dramatically. The organisation uses the 14 TB array to handle its virtual machines, which run a variety of applications including mission-critical database servers.

Although increased performance was the major benefit, the green storage benefits were impressive, both in terms of power usage and the reduction in physical footprint and in the physical materials needed to achieve Intercept IT's goals. "The biggest green credential comes from the ability to thin provision, which involves the overallocation of storage," Collins said. Generally, with direct-attached storage (DAS), server owners will ask for more storage than they need, which can lead to the provisioning of, say, 3 TB of storage even though the amount used is far less. That leaves large amounts of wasted storage, resulting in empty, spinning disks. "With thin provisioning, we can make it look like a 3 TB storage array, even though we're only using 100 MB," he explained.

RamSan SSDs reduce power, space costs: Odyssey

Brad Massey, director of IT at transportation and logistics firm Odyssey Logistics & Technology, also initially aimed for performance when he chose SSDs for his data centre. Originally, his team used solid-state as a means of increasing performance at the company's primary data centre in Charlotte, N.C. The company had been using EMC Clariion hard drive storage arrays to store data held in its production database. To offset the need for higher-performance servers, Odyssey decided to switch out that Clariion CX3-40 unit, which contained 90 73 GB drives, and instead install a pair of RamSan SSDs from Texas Memory Systems. The company used a RamSan 400 with 128 GB of DRAM for extra speed, complementing it with a RamSan 500 containing 2 TB of slower flash memory, with a 64 GB DRAM cache.

"Some of the production database runs on that RamSan equipment," Massey said. "In particular, the RamSan 400 handles the redo logs, the undo table space and temporary table space -- the things that need super-high performance."

The company, which made the switch a year and a half ago, found that the SSDs also brought unexpected power and space savings in addition to the performance increase. The two RamSan arrays eliminated the need for the 90-disk CX3-40 at the Raleigh site, saving the company half a rack's worth of space. The company began to realise that it could use solid-state technology as a means of greening its data centres, in addition to increasing performance. "Because we colocate our systems in third-party data centres, if we can save footprint in those data centre facilities, it saves us money as we contract the amount of rack space we use there," Massey said. "We were able to green our infrastructure by replacing a large amount of disk-based storage with another 3U RamSan storage array."

For every rack Odyssey saves in the data centre, it reduces its operational overhead by approximately £1,400 a month as a result of the reduced power and space costs associated with its storage. Consequently, the company has decided to purchase a third RamSan array -- a 630 model with 5 TB of storage, which can expand to 10 TB -- to replace a large proportion of the hard drives in its secondary data centre in Raleigh. This will eliminate an EMC CX500 containing 105 73 GB drives. It will also be able to eliminate at least two-thirds of the 90 73 GB drives in a companion CX300 array, saving a further £1,400 per month and lending credence to the company's corporate social responsibility stance.

Green storage technology saves money

More companies are developing green storage initiatives in the UK, with 43% of 136 European respondents to our recent survey either developing green initiatives or planning to do so. With organisations emerging from a recession and pressuring IT departments to cut costs and drive efficiencies into the infrastructure wherever possible, green storage technology is becoming an increasingly important vector. Companies such as Odyssey and Intercept IT are good examples of how many firms, originally driven by performance, are finding unexpected cost savings when going green.

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