NAND Flash Solid State Storage for the Enterprise

NAND Flash-based solid state storage (SSS) solutions, as they exist today, offer unparalleled performance combined with a level of data integrity and availability for mission-critical data that matches and potentially exceeds storage solutions based on mechanical, magnetic drives. Long associated with consumer electronics, NAND Flash has become a viable storage medium for commercial and governmental information systems, often referred to collectively as enterprise applications. It is well established by now that SSS solutions outperform storage systems based on hard disk drives (HDDs), even when HDDs are combined into large, multi-disk, striped arrays, shortstroked, or managed in other ways to increase performance. Less well known, however, due to some lingering misperceptions about NAND Flash as a storage medium, is the fact that NAND Flash-based SSS doesn’t just outperform its mechanical counterpart—it also significantly improves on data integrity (confidence that what you put in for storage is exactly what you get out) and availability (confidence that your data can be retrieved whenever you want it). Past comparisons between SSS and mechanical drives have frequently focused on single devices—how one SSS drive stacks up against one mechanical drive. However, enterprise computing environments rarely rely on isolated direct attached storage (DAS).The value of SSS becomes more apparent as used in real world data centers: as part of network attached storage (NAS) systems or storage area networks (SAN), where SSS can simultaneously increase the performance while greatly reducing the overall complexity and resource costs of data centers. 2 The Solid State Storage Initiative Recognizing the dramatically escalating interest in solid state storage, and thus an increased need for accurate technology information, education, and standards development, the Storage Networking Industry Association (SNIA) formed a new body in 2008, the Solid State Storage Initiative (SSSI). The SSSI immediately pursued the formation of the Solid State Storage Technical Work Group (SSS TWG) which works hand-in-hand with the SSSI. Many educational articles, presentations, and tutorials are being developed and made available to the public by the SSSI, with support from the SSS TWG, to fulfill its mission of fostering the growth and success of solid state storage in both consumer and commercial environments. This paper is a collaboration of the members of the SSSI. It is being made available to the public to provide information needed to understand this new solid state storage technology. No matter how the future of solid state storage plays out, the SNIA and its SSS Initiative and TWG will play an important role. The ultimate goal is to further the interests of solid state storage through education, standards development, and overall promotion of appropriate SSS deployment. The group will be a resource to users and the solid state storage community in defining, testing, and refining the rapidly developing solid state storage market. For more information about the SSSI, visit www.snia.org/sssi In and of itself, NAND Flash does have some performance peculiarities and some reliability challenges, but this paper will show that when combined with good management, NAND Flash-based SSS is a high-performing, highly reliable storage solution. This paper will discuss: • background information about the evolution of NAND Flash, • the challenges of using NAND Flash as a storage medium, and in particular, those that have the potential to affect data integrity and availability, and • ways that well-designed controllers and management software manage NAND Flash to simultaneously achieve both performance and reliability.