What is the best approach when it comes to green storage? Do you go with fewer large-capacity drives or many smaller drives with idling and power-sharing technologies to reduce consumption?
Or do you just bite the bullet and go all-SSD right now?
That last option may be a bit too pricey for the average data center at the moment, so any green storage strategy today will have to assume a fair number of mechanical drives.
On the one hand, you have companies like Western Digital, which just came out with the 2 TB Caviar Green 3.5-inch drive, which the company is aiming at video and media library catalogs, but can also form the foundation of an archiving/backup solution. The company has loaded it with energy-saving techniques like IntelliPower and StableTrac that allow the device to self-adjust its balance and spin speed and keep an eye on caching algorithms. It's a lot of drive for a mere $300m but is it necessarily a greener solution than, say, the Massive Array of Idle Disks (MAID) approach touted by Nexsan and others?
According to George Crump of Storage Switzerland, MAIDs are effective but only if data management tools can make maximum use of active drives. It does no good to put data onto a disk only to have it spun back up a few minutes later to retrieve it. Any array will need a management stack that can properly group data and place it on the system to ensure minimal energy use. It also helps if this process is automated to save your admins' workaday sanity.
Virtualization has also made shared storage as common as apple pie, but even here you need to have the right oversight to ensure an energy-efficient operation, says Scott Lowe, CIO of Westminster College in Fulton, Mo. Thin-provisioning, data deduplication and a host of other tricks should be part of the mix, but you also need to calculate your disk spindle/capacity requirements to make sure you're not running more drives than you need at any given moment.
Which system offers the most efficient operation? That's almost impossible to determine, considering vendors have become experts at couching performance in the best possible terms for them. But the Storage Network Industry Association is hoping to level the playing field somewhat with a new toolset for measuring and quantifying storage consumption. The Green Storage Power Measurement Specification includes a Green Storage Taxonomy to classify individual systems according to consumption characteristics and application environments, and a Power Measurement Metric that offers a baseline for things like idle-mode power usage.
In many data centers, greening up the storage array has taken a back seat to other power-saving measures like server consolidation and HVAC upgrades. But storage can become quite the energy hog if left to its own devices. A modest investment can generate a substantial savings -- and that is the best kind of green.