What is 3D NAND?

If you keep up with hard drive technology, you’ve likely heard of 3D NAND memory storage technology and you’ve probably read in many articles that it will effectively “kill” the hard drive. But what is 3D NAND technology and how and why does it have the potential to put an end to the decades-old hard disk drive?

nand 2It’s important to keep in mind that HDDs have been struggling to keep up with the modern need for data storage capacity, which has increased basically exponentially over the past decade. HDDs can store about 10 TB tops, which constitutes a huge amount of data in most cases, but given the way “big data” has become the latest necessary marketing tool, 10 TB often doesn’t cut it for top-tier businesses with terabytes of information to sort.

Then there’s the category of performance. When such tremendous amounts of data are being read and written, the rate at which information can be sorted by a drive makes a huge difference to users. In this arena as well hard drives have struggled to remain competitive; in terms of rotational speeds, HDDs have trouble moving past the 15K RPM. The models coming out today tend to boast of modest improvements in speed, but in general there’s a clear challenge of boosting speeds that relates directly to the hard drive’s innate design. Because they rely on a spinning disk and a magnetic arm that writes data on the disk, there’s just too many moving parts for the read/write speeds to surpass a particular metric.

These issues have all led to hard drives moving from an excellent portable option for standard drive users to becoming more of a capacity-related decision. Flash and SSDs were having trouble getting to the storage capacity of HDDs, so that became their major selling point among server-requiring companies.

Unfortunately, it seems that this advantage will too be phased out of the hard drive’s arsenal. This has happened in large part due to the solid-state disk’s evolution into multi-level cell technology. Multi-level cell or MLC uses multiple charge states and voltage levels to store four different values representing either 00, 01, 10, or 11 in binary code. This allows for extra quick processing in extra small spaces, but due to the closeness of the voltage tolerances in MLC, the endurance (or measure of the lifetime of the memory) of the NAND tends to be significantly lower than that of the single-level cell technology utilized by earlier iterations of SSDs.

Still, MLC is much cheaper than SLD because of its increased capacity capability despite using the same number of cells. In addition, technological breakthroughs have made MLC a little tougher and more viable for larger enterprise use.

nand3This all made SSDs a more competitive contender in the drive race, but the next iteration of MLC, triple-level cell, is what is likely to blow hard drives out of the water. Triple-level cell technology seems to imply that the cells store at three levels, but in reality its works so that three bits of data can be stored across eight voltage levels that range from 000 through 111. As with the transition from MLC to SLC, the reduced voltage tolerances between states causes the endurance of TLC to be lower than SLC. That said, it remains good enough for enterprise-class products that are cheap enough per terabyte to be worth the risk.

That means that, as one analyst put it, “the introduction of 3D TLC NAND, in conjunction with data reduction technologies like compression and deduplication, has reduced cost of all-flash systems using this technology to a point that they are comparable with high performance (15K) hard drive systems when looking at the total cost of ownership.

In other words, IT businesses may want to prepare for a major turn over in data storage technology.

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