Persistent storage that's just about as fast as RAM is widely held to be a year or three away from giving the server and storage industries a generational shakeup, and that change is now rather closer after US outfit Everspin started shipping samples of 256Mb Magnetoresistive random-access memory (MRAM).
MRAM looks like DDR3 or DDDR4 RAM and motherboards think it quacks like DDR. But MRAM is non-volatile – data doesn't disappear when power does – while also being rather faster than Flash. Just about everyone who's anyone in the hardware industry is therefore working on something like MRAM, because really fast persistent storage has lots of lovely uses.
Everspin's currently the only company selling this kind of stuff, but until today only in 64 megabyte chunks. Giving over a DIMM slot to just 64 megabytes of storage is not going to make MRAM mainstream. 256Mb is therefore a handy step towards making it easier to consider using MRAM more widely. Everspin says it also expects to sample a 1GB MRAM product by year's end.
The DDR interface is lovely and fast – DDR4 RAM can hit 19,000 MB/s – and Everspin is claiming write times 100,000 times faster than NAND Flash. That speed comes, in part, because there's no need to traverse SATA interfaces or a network.
There's a host of issues before this stuff becomes a mainstream option, starting with server-makers needing to accommodate MRAM so that machines operating systems can make MRAM work and understand it's a persistent tier of storage even though it lives in a DIMM slot. IBM has shown off a driver for Power8 Systems and Everspin says it's chatting to other server-makers too. So that box is partly ticked.
Density is another thing to worry about: servers can hold only so many DIMMS and the kind of application that likes fast storage also likes lots of memory. Everspin says it's working on 6GB MRAM, which will help with density, and is confident server-makers will rise to the challenge.
The there's cost. Everspin wouldn't give us a firm number for a 256Mb product, only saying it will be competitively priced compared to the cost of hardening a server to keep RAM electrified.
But the company feels it has cost covered in the long term, because its MRAM is manufactured on a 300nm wafer, a cost-effective process.
Things are clearly about to heat up in storage-land! ®