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The non-volatile memory revolution: Bigger than SSDs

NAND flash SSDs have revolutionized the storage world in the last 10 years. But non-volatile memory (NVM) is a much bigger deal than SSDs could ever be. Here's why Intel and Microsoft are behind it.

The Wintel band is getting back together. NAND flash SSDs have revolutionized the storage world in the last 10 years. But non-volatile memory (NVM) is a much bigger deal than SSDs could ever be. Intel and Microsoft are behind it.

Why?

Flash SSDs replace rotating disks with much faster devices, but the entire I/O stack is the same. So all the issues of writing data to a device remain - latency, errors, coordinating multiple buffers. SSDs are only a faster disk.

NVM, on the other hand, isn't simply faster. It enables something often called storage class memory (SCM) - memory that can be used as storage because it is persistent.

In its purest form SCM eliminates the difference between DRAM and storage drives. Instead of memory + storage, we could have a single layer of persistent memory.

In the meantime. . .

Of course we are a ways off from that, because it will be years before SCM products are price competitive with NAND flash. But NVDIMMs, sitting on the memory bus, can still speed up our systems tremendously.

Plexistor, for example, has built an NVM-aware file system that improves I/O performance by 6 to 8 times and reduces latency to less than a tenth of today's file systems. (For a deeper dive, see my piece on StorageMojo.

The Wintel band is getting back together

Since CPU performance gains have slowed to a crawl, the improvements promised by NVM and SCM are driving big investments by major players. Intel's 3D XPoint. Microsoft is working on it. HPE's Persistent Memory.

Other SCM technologies are coming to market, such as MRAM and RRAM. This is the beginning of a radical change in system architectures - and not a moment too soon.

The Storage Bits take

As is true with many innovations in computer technology, NVM and SCM return us to features we enjoyed in the distant past. Magenetic core memory also had persistence which made it popular - even after DRAM became much cheaper - in places with lousy power.

The IBM System 38 had a single memory layer as well, using disk as a virtual extension of the memory space. These architectures aren't new, even though many people have forgotten - or never learned - that they existed.

But the coming technologies are really fast - and while not as cheap as flash - some, such as 3D XPoint, will be cheaper than DRAM. While the volume will be in PCs and notebooks, I expect great things in larger storage systems as well (for a detailed example, check out the Nova file system from the recent Non-Volatile Memory Workshop.

Courteous comments welcome, of course.