MASS DATA STORAGE ROADMAP POINTS TO FURTHER GROWTH IN NAND AS WELL AS HDD, TAPE AND OPTICAL TECHNOLOGIES
Mass data storage technology for digital electronic systems is evolving and expanding in importance and impact.
A range of technologies
From its origins primarily in high-end computing and business systems in the 1940s and 50s, mass data storage has broadened to encompass a wide range of technologies and applications. Current technologies include solid state non-volatile flash memory based on NAND semiconductor cells, ferroelectric, magneto-resistive random access memory, magnetic recording on rigid disks and tape, and a number of different optical storage technologies. The list of emerging mass data storage technologies that have already or will soon enter the mainstream continues to increase, including solid state phase change (“Ovonic”) memory, hybrid flash/disk drives, memristor storage, spin-torque MRAM or other magnetic spin based memories, and optical holographic based storage.
NAND flash memory
NAND flash memory technology continues to grow in commercial importance, displacing the smallest diameter (<1.8”) hard disk drives (HDD) and performance enterprise hard disk drives. Due to higher cost of manufacturing but lower storage capacity, flash memory is complementary to hard disk drive technology but there are some applications where they are approaching cost parity. Flash memory is expected to continue to play a larger role in both low and high-end computing systems, as prices decline and capacity and reliability improvements are realized. The price decline may be faster than that expected from Moore's Law, enabled by capacity improvements from multi-bit cells and 3D multi-layer flash memory, although scaling limits due to small cell size and fundamental signal-to-noise limits may eventually limit the technology's advance. Flash memory is transitioning into three dimensional structures to continue the increase in storage capacity per chip as planar flash memory line widths have gotten close to their minimum.
Magneto-resistive MRAM technology based non-volatile memory products are now established in the marketplace, although at fairly low capacity and high prices. The long-term success of this technology may be critically dependent upon a successful transition to more areal efficient and less costly spin torque or thermal switched cells, which could enable higher capacities and a wider application spectrum. The emergence of spin-torque (ST) switched MRAM products is indicative of a vibrant and growing progress in this technology. Other storage technologies, such as phase change memory have had some military and industrial uses but have yet to gain large market share, although the Intel/Micron announcement of 3D Xpoint technology is likely a form of phase change memory. 3D Xpoint is expected to play an important intermediate role between DRAM and flash memory.
Magnetic recording-based hard disk drive (HDD) technology continues to play a large and important role in mass data storage. With about 468M shipped units in 2015, and expected volumes slowing to ~396M units by 2020, HDD technology continues as a cost–effective non- volatile online storage solution. Price reductions and cost efficiencies have led to vertical integration of all but one of the remaining three HDD manufacturers, and further consolidation of head, disk, electronics and mechanical suppliers. Enablers for continued HDD areal density and performance improvements include CPP GMR (current perpendicular to plane giant magnetoresistance) heads, heat assisted magnetic recording, shingled magnetic writing, bit patterned media, advanced signal processing, and improved security through disk data encryption.
Tape and optical storage will continue to play primarily an archival and data transfer role. Tape technology has benefitted from the standard LTO format and now enables file based storage on the tape with the LTFS file system on LTO-7 tapes. Optical has been aided by technology improvements such as the Blu-ray disc with write-once archive capacities as high as 300 GB per disc and new holographic storage start-ups promise capacities far beyond those currently achievable with Blu-ray discs.
The continued success of optical storage will be dependent on keeping resolution of physical content distribution higher than can easily be downloaded via the Internet, since online distribution is becoming more popular. Continued increase in storage capacity of optical discs depends on use of shorter optical wavelengths or innovative component technologies. The near-term future of this industry is mainly dependent on the realization of advances in multi-layer and near-field technologies.
Finally, optical storage products face increasing competition from flash memory, wideband data links, and external hard drives. The ever-increasing demands of the storage market, however, will probably allow modest unit and revenue growth, at least for the next three to five years (mainly due to increases in BD sales and possibly 100-300GB sales).
Mass data storage roadmap
The Mass Data Storage chapter of the 2017 iNEMI Roadmap covers a wide variety of storage technologies, including both well-established and emerging technologies. It covers technologies in the areas of solid state, magnetic storage and optical data storage. It is an excellent tutorial on mass data storage, and also points out the trends and developments that are required to meet the mushrooming growth in data storage capacity. Get additional information about the iNEMI Roadmap.