The Case for Server SSDs

While the market isn't exactly huge for SSDs just yet, there are customers in need of the technology's increased performance and low power consumption.

By James E. Gaskin

SSDs (solid state disks) are high on each "hot for 2010" list. But which customers will pay the higher costs for SSDs to leverage their higher performance and lower power consumption? Your best bets are customers who choose solutions based on the cost per IOPS (input output per second) rather than those who compare cost per gigabyte.

"The SSD market is very small now, maybe 4 million units sold last year out of about 550 million units total," says Greg Wong, principal analyst at Forward Insights. In other words, it's less than 1 percent of the hard disk market.

So focus on three areas: boot drives and high-performance applications in which SSDs replace traditional spinning hard disks, and a new area, PCIe (Peripheral Component Interconnect Express, sometimes written PCI-E), which is an expansion card interface tied to the system bus rather than the disk subsystem.

Boot disks are excellent SSD applications because faster is better, 16GB is more than enough data storage, and data read speeds are the key. "IBM offered SanDisk 16GB drives as a boot option on one server model and got a double-digit adoption rate," says Wong. The move over the last several years to stacking hundreds of virtual servers on one physical server makes fast booting more critical than ever.

THE NEED FOR SPEED
"You need speed to recover images quickly," says James Bagley, senior analyst for SSG-Now. "Dell offers an SSD boot disk as a standard option in its DAS [direct-attached storage] systems." Over the next year or two, servers acting as virtual server hosts will migrate toward the PCIe SSDs hooked directly to the system bus.

Look for applications in which customers have been using 15,000-rpm drives in subsystems to stripe data across dozens or hundreds of drives to increase read performance, suggests Bagley. "A bunch of 15k spindles are much more expensive than a few SSDs." Video studios, on-demand video servers, and heavy simulation users like oil and gas companies will actually improve performance and save money with SSDs over high-speed spinning platters.

Support vendors are ramping up, according to Bagley. New SSD controller boards and components from vendors such as SandForce are improving the speed of inline compression, deduplication, and encryption used by SSDs. Other names to look for are Intel, STEC, OCZ, Fusion-io, and Pliant Technology. SSD units fit into existing drive subsystems today just like traditional drives, easing implementation.

E-COMMERCE A GOOD BET
Another place for SSDs is in situations where speeding up a small part of the data has unusually large value. "EMC found that putting about 5 percent of the typical data set on SSDs provided a speed increase of a couple orders of magnitude," says Bagley. For example, think of e-commerce applications: Initial order information will be accessed constantly for the first 24 hours, then maybe twice over the next few years.

The price differential will continue to narrow, down from 10x higher for SSDs today to the 7x range in about five years, according to Wong. Today's models are SLC (single-level cell) devices, emphasizing speed and endurance. MLC (multilevel cell) devices, just on the horizon, are roughly half the cost of SLCs but trade some performance and endurance for lower costs.

"In five years, the majority of SSDs will be MLCs," says Wong. "That will bring the price gap down to the 4x range over traditional hard drives." That's still more expensive than spinning platters, but priced close enough to make the speed boost and energy cost savings an easy choice.