IRVINE, Calif. -- Universal flash storage (UFS) is poised to replace e-MMC as devices with embedded memory continue to demand more capacity and higher performance. But both memory technologies will continue to co-exist for some time.
Scott Beekman, director of managed NAND memory products for Toshiba America Electronic Components, says that although e-MMC is still the memory device of choice for mobile applications because of its low power consumption and cost, UFS is in a better position to meet the higher performance demands that are expected in the coming years from mobile devices.
e-MMC has seen wide adoption for use in smartphones, tablets, games, servers, printers, and automotive systems, notes Beekman, but it is limited performance-wise since it only supports half duplexing. (It permits either reading or writing between the host processor and an e-MMC device, but not both at the same time.)
The ability of UFS to support full duplexing, where reading and writing occur between host processor and UFS device at the same, says Beekman, provides a significant boost in performance that accommodates features such as higher quality video and faster network speeds on mobile devices. Capacity and density of the memory are less of an issue, he says. What’s important is the speed of the interface to the memory as applications become more complex and more demanding.
JEDEC, developer of global open standards for the microelectronics industry, recently published version 2.0 of the UFS specification, which was designed to accommodate mobile applications and computing systems that need high performance and low power consumption. Link bandwidth has been increased from 300 MB/s in UFS v1.1 to up to 600 MB/s per lane, and multilane support has been introduced, allowing up to 1.2 GB/s per each data transfer direction.
Two complementary standards were also released. The JESD223B UFS host controller interface version 2.0 is meant to simplify the design process by defining a standard host controller interface so system designers can create a common host controller software driver layer to work with UFS host controller hardware from different manufacturers. Meanwhile, the JESD223-1 UFS host controller interface unified memory extension defines the interface between the UFS driver and the UFS host controller.
eMMC has improved over time, notes Beekman, but there are limitations to the architecture, in part because it has to stay backwards compatible. UFS is a new architecture created from scratch.
Brady Wang, principal analyst with Gartner, says UFS offers more IOPS, higher capacity, better bandwidth, and optimized performance for multi-threaded applications in comparison to e-MMC, which has a maximum speed in its latest incarnation, version 5.0, of 400 MB/s.
Gartner expects to see initial production of UFS to begin in the middle of next year, with adoption beginning in 2015, although that adoption will be constrained by its higher cost and power consumption, as well as the fact that UFS is not backward compatible with the well-entrenched eMMC. Wang says demand for high performance memory systems is growing. “Although the power consumption of UFS is higher than eMMC, its energy efficiency is better.”
UFS is particularly well-suited for ultrabooks or tablets which have high capacity battery, as well as high-end smart phones, Wang says, but e-MMC will continue to dominate the market for the near future, and is still the best option for low- to mid-cost mobile applications. The support of chipset makers will determine the initial adoption of UFS, while commercialization of UFS will be driven by receptive OEMs and device makers.