Flash storage too good to resist

While cloud computing and virtualization have transformed server infrastructure dramatically, it's the rise of solid-state drive/flash technologies that have enabled a storage renaissance.

Flash storage will continue to bring a much needed boost to the enterprise landscape. From Fusion-io's IPO last year to the recent launches of a host of venture-backed startups like Nutanix and Tintri, there's a lot going in the world of flash storage.

As an increasing number of applications and databases are virtualized and deployed to the cloud, traditional disk-based storage arrays are creating serious performance bottlenecks that are rendering them increasingly irrelevant. Virtual and cloud-based infrastructures consolidate workloads on a smaller number of servers, which in turn quickly overwhelms disk-based architectures.

While server, network, and processor performance have followed Moore's Law, the performance capability of a single disk spindle hasn't changed significantly. Flash, on the other hand, offers far greater performance. A single commodity SSD is 400 times faster than a single hard disk for example. This is just one reason why Amazon Web Services' new DynamoDB offering runs on SSD drives instead of a traditional disk architecture.

Industry giants EMC and NetApp have begun to offer "flash as cache" solutions that can be bolted on to their existing products, though critics point to two significant drawbacks with this approach: adding flash to existing solutions can be incredibly expensive; and their function is limited to a read cache.

The second limitation is critically important, according to Ed Lee, an original member of the Berkeley RAID team in the 1990s who is now lead architect at Tintri. "With a bolt-on flash as cache, you're lucky if 30 percent of the application traffic benefits from flash. Basically, you're still getting disk-level rather than flash-level performance," Lee said in an e-mail interview.

As an alternative to the bolt-on approach, a wave of startups have launched with flash-based offerings. By incorporating techniques like inline de-duplication and compression, new solutions are able to reduce the per-gigabyte cost of flash and offer high-performance products at a competitive price point.

A number of storage vendors--including Violin Memory and SolidFire--offer 100 percent flash arrays, touting the enormous performance enhancements that their solutions offer. While this is certainly true, it doesn't do much to address the prohibitive cost per gigabyte of flash.

Tintri pushes what it refers to as an "intelligent flash storage" approach--a hybrid array that combines both flash and SATA (Serial Advanced Technology Attachment), which comes at a much cheaper price point. According to Lee, all-flash arrays aren't necessary the vast majority of the time and it's too costly to simply throw flash at performance problems.

"De-duplication and compression combined with a hybrid system that automatically places inactive data on disk can deliver the same level of performance as an all-flash approach--without the manual work that a tiered approach requires."

The flash storage market is crowded, and growing larger by the day. EMC recently announced its VFCache solution (project Lightning), a server-side flash PCI card, similar to Fusion-io. NetApp, its main competitor, has alluded to a similar release in the near future.

Which approach will win out remains to be seen, but it's clear that flash-based storage has arrived--and that it's here to stay.