VFCache and Project Thunder use PCI Express (PCIe) flash technology to accelerate application read performance. EMC began offering flash technology in storage arrays in 2008, when it sold solid-state drives (SSDs) as an option in its SAN arrays. VFCache is its first PCIe flash card. Putting flash closer to the CPU accelerates application performance more than placing it in the storage array.
VFCache consists of 300 GB PCIe cards -- EMC is using single-level cell (SLC) flash from Micron and LSI -- along with EMC-developed software for flash management and wear leveling. The software sits on the server and acts as a filter driver to determine which data gets cached. EMC considers its VFCache an extension of its FAST auto tiering software architecture, although FAST is not required to use VFCache.
VFCache has limits. Only one card can be used per server and only applications on that server benefit from the performance boost. EMC says Project Thunder will address those limitations.
Barry Ader, EMC’s senior director of product management for flash products, said the vendor’s testing showed a threefold increase in throughput and 60% reduction in latency for applications running on EMC VMAX, VMAXe, VNX and VNXe storage arrays. VFCache can be used with other vendors’ storage, Ader said.
By caching hot data, VFCache eliminates the need for that data to travel from the storage array and through the network. EMC claims VFCache is the faster than other PCIe flash caching products on the market because it processes the management functions directly instead of offloading processing to the server CPU. Ader said using VFCache with storage arrays also allows for better data management and protection than using server flash cache only.
“Using PCIe flash as direct attached storage inside the server creates a couple of problems,” Ader said. “One is manageability. How do I figure out which storage should sit on the PCIe card? How do I protect the data if it’s not sitting on a storage system with five-nines of availability? And how do I scale the storage? We believe customers need performance, but they also need intelligence and protection.”
Fusion-io, the dominant PCIe flash vendor to date, counters EMC’s claims by arguing that their products greatly improve performance on lower-cost storage or commodity servers while EMC’s VFCache is designed for high-priced storage arrays. Fusion-io says its products can eliminate the need for SANs.
Arun Taneja, consulting analyst of the Taneja Group, said VFCache is a sign from EMC that it sees server flash as a key technology in the SSD market.
“When EMC recognizes it’s missing something, it will quickly fill that gap by doing something internally or grabbing the best company in the marketplace,” Taneja said. “EMC had the choice of buying Fusion-io, or doing something better by itself. They caught this wave early enough, and they have a product now.”
VFCache also works in split card mode, which lets customers use part of the cache as a DAS device for temporary data such as swap files, temp files and log files that don’t require backup.
EMC has not released pricing details for VFCache, although the product is generally available. Ader said it would be priced competitively with other server PCIe flash products.
EMC plans to add features such as data dedupliction for cached data, better integration with its storage array, active-active cluster support, as well as larger capacity flash over the next year. Ader said a multi-level cell (MLC) flash option may be added in future releases.
EMC will begin an early-access program for Project Thunder in the second quarter of this year. Project Thunder is a shareable storage system that will run multiple PCIe cards and use a high-speed network -- probably InfiniBand or 40-Gigabit Ethernet -- to reduce latency.
“[VFCache] is not shareable,” Silverton Consulting president Ray Lucchesi said. “If you have a lot of storage you wanted to speed up, you’d have to go to SSDs. Thunder is a sharable storage system connected to a server.”
Taneja added that Project Thunder is a logical extension to VFCache.
“Once you have this fundamental cache working, now you can extend it to a network-based device that services a number of arrays downstream,” Taneja said. “Project Thunder is extending the cache from one server to multiple servers, but at a higher horsepower level than you would get from putting it directly in arrays. I/O acceleration from SSD drives in the array is like peanuts compared to what you get from PCIe.”