Flash storage moves closer to CPUs

In a bid to maximise the speed advantage of solid-state storage, more vendors are promoting approaches that move it closer to the CPUs that process stored data.

STEC and OCZ Technology Group both introduced flash storage components for PCI-Express (PCIe) this week, with STEC moving into this market for the first time.

STEC is making a splash with both its own line of hardware modules and a software platform that can work with solid-state components from other vendors.

Rather than a simple replacement for spinning disks in centralised storage arrays, solid state increasingly is being looked at as a component within servers to store heavily used data or act as a cache. Fusion-io led the way with this approach, and STEC, one of the biggest suppliers of flash to system vendors making traditional SSDs, is now joining in.

“Solid-state storage adds some upfront costs, and building it into servers can add others, but there may be eventual savings for some enterprises,” according to Enterprise Strategy Group analyst Mark Peters. “The payoff can come in reducing delays,” he added.

“We’ve been so brainwashed in the business that the way you measure storage is cost per gigabyte,” Peters said. “No one’s storing anything for the sake of storing it. You’re storing it because you may use it. A storage architecture that gets the data to the server more quickly, such as a PCIe card in the server, can justify the added expense,” explained Peters.

“STEC’s EnhanceIO software, which is also sampling to early access customers, is likely to have a bigger impact than the PCIe cards because it will work with hardware from many vendors,” Peters said.

“Interest in server-based SSDs is growing, but it ultimately may not be the best strategy for enterprises with large, virtualised data centres,” he said.

“You lose shareability, because it’s now fixed to that server,” Peters said. “Centralised SSDs offer more management flexibility and don’t have to be included consistently across all the servers in a data centre to realise their benefits. For smaller organisations with fewer servers, server-based SSD caching may work well,” he said.

STEC on Thursday introduced the Kronos PCIe Solid-State Accelerator module family, along with its EnhanceIO SSD Cache Software, which it says can work with the Kronos line or nearly any other SSD on the market. The company claims that the two products can dramatically cut the cost of a data centre by reducing the need for very fast storage systems and other techniques for accelerating applications.

“The Kronos and Kronos Turbo cards, with capacities ranging from 240GB to 980GB, can be used for primary storage within a server. But they are designed primarily to cache copies of frequently accessed data very close to the CPU for faster performance. This eliminates the delays caused by switches, RAID controllers and other components in a traditional storage system,” said Scott Stetzer, STEC’s VP of technical marketing. STEC claims its new technology can cut latency from hundreds of milliseconds to 30 nanoseconds if a company is migrating from a traditional SAN (storage-area network) or iSCSI (Internet SCSI) arrangement.

SSDs cost more per gigabyte than HDDs (hard disk drives). But because SSDs offer faster data retrieval, they reduce the need for expensive, fast-spinning hard disk drives and for techniques to maximise the speed of those drives, which can involve buying many disks and not using most of their capacity. “Putting the SSD in a server can boost performance even more by eliminating multiple hops across a network for the most-used bits of data,” said Stetzer.

Within the Kronos modules, STEC has taken another step to boost server performance. The cards offload I/O tasks that with some similar PCIe products would have to be performed by the CPU, the company said. “This frees up chip cycles that are needed for other work, especially in busy virtualised servers,” Stetzer said.

“This offloading feature sets STEC apart from Fusion-io, the incumbent vendor in this market, giving STEC at least one key differentiator to help it seize market share,” ESG’s Peters said. However, it will remain hard for STEC and other challengers to gain ground on Fusion-io, given existing supplier arrangements with system vendors, he said. Breaking into the PCIe business is a major goal for STEC, which last month lowered its financial forecast for the current quarter because of growing competition in its core business. STEC’s stock has fallen by more than 50% since February.

The Kronos cards can read and write sequential data at 1.1GB per second and the Kronos Turbo at 2.2GB per second, according to STEC. They are now shipping to server makers in sample quantities. A Kronos Bi-Turbo line, with capacities as high as 1.95TB and a read/write rate of 3.6GB per second, is due early next year, Stetzer said. All the cards will be available in both SLC (single-level-cell) and MLC (multilevel cell) versions and will use STEC features for high reliability, he said. They will come with a five-year warranty.

STEC’s announcement on Thursday follows OCZ’s introduction of a new PCIe SSD that it said has twice the performance of its previous product. The Z-Series SSD R4 comes in half-height and full-height cards with capacities ranging from 300GB to 3.2TB and can read data at a rate of 2.8GB per second, according to OCZ. Unlike OCZ’s earlier products, the cards are intended for sale directly to server makers rather than to users.