By Kevin Komiega
Storage systems are major offenders when it comes to power consumption in the data center, but in the quest for energy-efficient technology the focus, at least so far, has been primarily on microprocessors and servers. So why has storage flown under the radar? It could be that, aside from reducing raw capacity, the industry has yet to come up with a clear-cut answer to the problem.
“There is not an obvious and straightforward approach to saving energy in the storage environment because disks are going to spin. The only way you are going to save is to stop them from spinning,” says John Webster, principal IT advisor with the Illuminata research and consulting firm.
Some vendors are doing just that. Copan Systems, for example, bases all of its virtual tape library (VTL) and archiving systems on a massive array of idle disks (MAID) architecture. MAID technology operates on the basic premise that not all disks need to be spinning all of the time. Only disks containing data being requested by applications need to be powered on, and they are turned off when not in use.
In the case of Copan, only a maximum of 25% of the drives in a system are powered on at any one time. This approach may be a fit for storing long-term, infrequently accessed data, but is less practical for primary storage.
Another approach is more-efficient capacity provisioning. So-called thin-provisioning technologies have been around for several years and, according to Webster, can improve disk utilization rates from 30% to 40%, to 60% or greater.
Thin provisioning lets users allocate just enough storage to applications, thereby reducing overall capacity requirements and associated power and cooling costs. Vendors such as 3PAR Data, Compellent, EqualLogic, LeftHand Networks, Network Appliance and, most recently, Hitachi with its new USP V high-end array all offer thin provisioning in some form.
There are still more data-management techniques that can be applied to reduce overall capacity, such as data compression, de-duplication, tiering, and archiving, which all add up to energy savings.
Eventually, however, users will need to buy more storage no matter how much software they throw at the capacity problem.
“A lot of hardware vendors are finally waking up to the reality that they have to tackle the power-consumption problem, but it looks like some of the promises they are making are still a ways out,” says Seth Sladek, a senior systems engineer at Cambridge Health Alliance.
Sladek manages storage on a daily basis and is constantly looking for ways to streamline his operation.
“We’re looking at archiving technologies to get data that isn’t being accessed regularly off of spinning disks,” says Sladek. “I’d like to see more energy-efficient drives. Today’s drives are certainly more-efficient than the 500GB drives of old that were two feet in diameter, but I think drive makers have just scratched the surface in that respect,” he says.
But Sladek says he is not completely willing to sacrifice performance for a lower electric bill. “I’m wary of the performance trade-off. Hopefully, drives will continue to improve in performance, but at the same time become more energy-efficient. It’s a double-edged sword,” he adds.
Drive manufacturers are conscious of their role in the power consumption conundrum.
“The amount of power consumption attributed to drives is relatively insignificant in small numbers, but when you move into the data center and take an average of 8 watts per drive and multiply it by hundreds of thousands you’re talking megawatts,” says Willis Whittington, senior product marketing manager for Seagate’s Enterprise Compute Business.
However, Whittington says there is a delicate balance between saving power at the drive level and providing the performance and capacity points users have come to expect.
“We can save power, but it’s at the expense of something else, and that something is usually performance, whether it be seek times, latency, or throughput,” says Whittington. “We could say to customers, ‘We can save you 20% on your electric bill if you let us take 10% off the performance of the drives.’ But users want more performance.”
Seagate has begun its own work on the power problem with the announcement of what the company calls PowerTrim Energy Efficiency, which is a set of features that together reduce the overall power consumption of its hard drives (see “Seagate unveils power-conscious 10K drive,” above).
Whittington claims PowerTrim helps energy-constrained data centers maximize efficiency with power consumption rated as low as 8 watts. The result is a drive that delivers a 34% reduction of power in idle mode, as well as a 33% reduction in operating power.
The Cheetah NS-the first Seagate drive to use PowerTrim-is a 10,000rpm hard drive based on the same platform as the speedier 15,000rpm Cheetah 15K.5. The Cheetah NS offers 400GB of capacity with lower power and cooling requirements than the 15K.5. The trade-off, of course, is a performance hit.
“There is no low-hanging fruit available when it comes to saving on energy costs, but there are a lot of little things that can be done. It has to be a holistic approach,” says Whittington.
Whittington notes that more-efficient power supplies and tighter integration between system workloads and drives could also yield power savings. “If we had better cooperation between the system and the drive and get power supply efficiency up over 80%, we could save more power,” he says.
Data growth ultimately translates into the need for more power. It’s the unstoppable force versus the immovable object. Something has to give.
Steve Duplessie, founder and senior analyst at the Enterprise Strategy Group, says that at least for now a hodgepodge of space-saving technologies seems to be the best-if not the only-approach toward stemming the tide of power consumption. However, he also expects vendors and users alike will begin to reassess how they build and implement storage infrastructures.
“IT needs to wake up and begin treating process changes, such as information lifecycle management [ILM], as ‘need to have’ instead of ‘nice to have,’ because that’s the only way they’re going to get close to solving these issues in the short term,” says Duplessie.
Storage vendors seem to be in catch-up mode when it comes to addressing power and cooling problems, slapping the “green” label on existing technologies or pledging more eco-friendly products in the future, but most of the initial progress is being made in other areas of IT.
“Servers are what you mostly hear about now, but the data layer is really where the problems are,” Duplessie says. “You’ll see a ton of both marketing hype and real-world data over the next six months that expose the real issues around data-center power and cooling.”
In an effort to develop some of that real-world data, a non-profit consortium called the Green Grid cropped up earlier this year to come up with ways to trim the data-center power drain.
The group, founded by AMD, APC, Dell, Hewlett-Packard, IBM, Intel, Microsoft, Rackable Systems, SprayCool, Sun, and VMware, is in the process of developing performance-per-watt metrics with a fixed set of benchmarks and interoperability standards for energy efficiency in the data center.
Green Grid members have stated that they will take a “holistic approach to addressing the entire computing eco-system.” Standards and metrics will be developed and applied to all IT equipment, including servers, networking gear, and storage, as well as non-IT equipment such as air conditioning units and overall facility design.
Several storage companies have joined the ranks of the Green Grid since its launch in February: Brocade, Cisco, Copan, EMC, Netezza, QLogic, Quantum, SGI, Storewiz, and Xyratex.
Seagate unveils power-conscious 10K drive
By Kevin Komiega
Seagate Technology recently announced a new hard drive that strikes a balance between capacity and power consumption. The 10,000rpm Cheetah NS drive is based on the same platform as the 15,000 rpm Cheetah 15K.5, but includes Seagate’s new PowerTrim technology for more-efficient power consumption.
The Cheetah NS also features up to 33% more capacity at 400GB, along with a 33% reduction in power and cooling requirements. This additional capacity and reduced cooling profile in the data center means that the Cheetah NS ultimately delivers a lower total cost of ownership.
“We took the 15K Cheetah drive design and boosted the capacity to give us an extra 100GB without losing too much in the way of performance,” says Willis Whittington, senior product marketing manager for Seagate’s Enterprise Compute Business. “We haven’t changed anything in the mechanics. The only thing we changed is the head design.”
Power consumption for the Cheetah NS drive is rated as low as 8 watts. The result is a 34% reduction of power while idle, as well as a 33% reduction in operating power compared to other 10,000rpm drives.
Whittington says users looking for higher IOPS-per-gigabyte transactional performance are likely to opt for the Cheetah 15K.5, while the new Cheetah NS is designed for users in search of a higher capacity, lower-cost option.
The Cheetah NS has a seek time of 3.9ms and is available with a choice of interfaces, including 3Gbps Serial Attached SCSI (SAS) or 4Gbps Fibre Channel. The drive is rated at a mean time between failure (MTBF) of 1.4 million hours and has a five-year warranty.
Seagate is now shipping the Cheetah NS to OEM customers, and the drive is expected to be available to the distribution channel during the third quarter of 2007.