Solid State Disk And Green

I saw a recent claim by Sun that Solid State Disk Drives (SSDs) consume 20% of the energy that traditional storage systems do. While I can't verify that to be the case, it makes sense. Texas Memory Systems, the veteran of the SSD space, recommends that for real power savings, companies should compare a SSD with a storage array that is configured to deliver the same level of performance that an SSD can.Typically, performance concerns focus on just a few applications that are critical for the data center and the other applications get brought along for the ride. To get the I/O requirements that some of these high-end applications require, organizations often purchase a storage array with very fast, power-hungry I/O compute engines, lots of cache memory, and stripe the information across many drives in the array, called wide-striping. Also, the drives typically used to build this wide-stripe RAID group are 15K RPM drives, which are the most power-consuming drives available today.

The cost to power this type of storage infrastructure is expensive and resource wasteful. Especially on traditional systems without thin provisioning, this wide-stripe RAID configuration creates volumes that are mostly unused capacity. Even with thin provisioning in place, the active volume on a large number of drives requires each drive in the wide-stripe to be active and drawing power -- the excess space on the drives can only be used for very inactive data that could have been placed on low-power SATA drives instead.

Compare this with a Solid State Disk Drive, especially an enterprise-class one with redundant fans, battery backup, and hard drive backup. On a per-GB basis, the actual power consumption savings are slight, but considering that this little box delivers the same or often better performance of a high-end storage array with lots of drives, the cost savings becomes staggering.

Power isn't the only issue, of course, with SSDs; performance and reliability are the hallmarks of SSDs. By offloading performance workload from the storage array, you also may be able to purchase a more moderate performing storage array with more traditional RAID layouts. This can save upfront acquisition costs, make better use of capacity, and once again reduce power consumption by not having to power unused disk resources.

George Crump is founder of Storage Switzerland, an analyst firm focused on the virtualization and storage marketplaces. It provides strategic consulting and analysis to storage users, suppliers, and integrators. An industry veteran of more than 25 years, Crump has held engineering and sales positions at various IT industry manufacturers and integrators. Prior to Storage Switzerland, he was CTO at one of the nation's largest integrators.