Magnetic RAM Remains Niche Memory for Now

TORONTO – Magnetic RAM (MRAM) may have the potential to replace DRAM and SRAM in many applications, but even the sole vendor shipping the nonvolatile memory (NVM) expects the transition to take time.

A Coughlin Associates report released this spring suggested MRAM was poised for a 50% compound annual growth rate, with MRAM and STT-MRAM revenue increasing from about $190 million in 2013 to $2.1 billion in 2019.

Tom Coughlin, the firm’s founder, said one of the appealing aspects of MRAM is its compatibility with CMOS processes. Also, because the processes are mature, it makes integration less daunting than the transition to 3D NAND. He said the evolution of MRAM is likely to follow that of flash — gaining traction in niche applications before it gets widespread adoption as costs go down and density improves. STT-MRAM in particular offers some advantages in terms of read/write and endurance, he said.

In an email interview, Gartner analyst Brady Wang said MRAM is finding use as a cache in SSDs, but its density is still too low, and it is generally used in industrial applications.

MRAM does have advantages over DRAM in that it’s non-volatile. Like NOR and NAND flash, he said, STT-MRAM retains data without continuous external power supplies, and it consumes less power. It can also scale better than SRAM because of its simple structure, which allows for increased shrinkage and potentially lower manufacturing costs.

In comparison with NAND flash, Wang said, STT-MRAM can switch between storing zeroes and ones without an intermediate erasing step, which is essential in flash memory and increases write latency. This makes designing STT-MRAM controllers much easier than designing NAND flash controllers.

Wang said Everspin Technologies is the only vendor shipping standalone MRAM chips (see image), with a current maximum density of 64 Mb. Densities of 128 Mb or even 1 Gb could be achieved in the next two years, with 1 Gb making MRAM suitable for use in consumer applications.

Joe O’Hare, Everspin’s director of product marketing, said its MRAM products (which the company began shipping more than five years ago) were used initially for industrial applications. The company has seen widespread adoption in factory automation, robotics, transportation, and medical applications. However, its biggest growth area is enterprise storage.

As densities increase, Everspin sees MRAM as a bridge toward the further adoption of NVMs, offering the performance of DRAM but becoming more of storage memory like flash. As emerging technologies shake out, he said, MRAM is poised to be one of the key choices for persistent, high-performance storage.

An example of MRAM use in enterprise storage is RAID systems, where the concern is recovering quickly from power loss, O’Hare said. MRAM is used to store metadata and storage system data, so if there is a power interruption, the system information is still held in nonvolatile MRAM and enables the RAID system to rebuild itself more quickly.

O’Hare said Everspin is finding a number of applications for MRAM in enterprise storage that don’t require the density of DRAM but can take advantage of an NVM. This market is sizable enough on its own. It’s not about price – system reliability is the driver.

Jim Handy, principal analyst of Objective Analysis, said ultimately price and density will determine whether MRAM becomes a viable replacement for DRAM or SRAM on a wide scale. Lower power consumption is appealing, but most organizations aren’t likely to make that TCO calculation. MRAM can be used to replace SRAM in some applications, negating a need for backup batteries, which are prone to failure.

Industries that value MRAM’s non-volatility (such as the banking industry for its ATMs) will pay a premium for it, Handy said. But at the moment, DRAM and flash are doing well with their own technology migrations, so there’s no immediate reason for replacing them.

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