3D NAND flash technology is revolutionizing the storage industry, and it’s crucial for professionals like you to understand its impact. This innovative technology offers higher density and lower costs compared to traditional planar NAND, making it an attractive solution for various applications.
However, it’s essential to be aware of the cyclical nature of the NAND flash market. Shortages and oversupply periods lasting about two years each can greatly impact prices. As of late 2018, the market is experiencing oversupply, leading to lower NAND prices.
When considering 3D NAND flash for your organization, carefully weigh the advantages and disadvantages, especially when it comes to QLC 3D NAND. Make informed decisions based on your specific application requirements and market conditions.
Embracing 3D NAND flash technology can give you a competitive edge, but it’s crucial to have a solid understanding of its capabilities and limitations. Invest time in learning about this game-changing technology to make the best choices for your organization’s storage needs.
Table of Contents
Question 1
Which of the following is not distinctive to 3D NAND when compared with planar NAND?
A. Vertical cell structure
B. Higher cell density
C. Lower manufacturing cost
D. Layered architecture
Answer
C. Lower manufacturing cost
Explanation
Memory cells in 3D NAND flash are stacked vertically in a layered structure. This structure results in a higher cell density compared with planar NAND, where the capacity of the chip increases with only a marginal increase in its size. However, 3D NAND flash technology has higher manufacturing costs compared with planar NAND, because the 3D layering adds complexity and steps to the manufacturing process.
Question 2
Which of the following is not a characteristic of 3D NAND flash memory when compared to NOR?
A. Higher density
B. Sequential writes
C. Faster reads
D. Faster erase times
Answer
C. Faster reads
Explanation
Among the benefits of NAND flash memory when compared with NOR memory technology are its higher density, sequential writes and faster erase times. However, 3D NAND has slower read speed and doesn’t offer the one-byte random access that NOR does.
NOR is considered a good option for code storage in mobile phones and other devices, while NAND and 3D NAND are recommended for data-intensive applications, such as SQL and NoSQL databases.
Question 3
Which of the following are benefits of 3D NAND flash memory compared with planar NAND?
A. Reduced power consumption
B. Improved reliability
C. Better write performance
D. All of the above
Answer
D. All of the above
Explanation
With more cells compacted into a smaller space, 3D NAND consumes power more efficiently. It’s also more reliable and offers better write performance.
Question 4
Which of the following negatively affects planar and 3D NAND flash durability?
A. Write amplification
B. Bad block mapping
C. Data compression algorithms
D. Wear leveling
Answer
A. Write amplification
Explanation
Write amplification is a key factor associated with flash memory degradation. It happens, in part, because data in a flash drive is read and written at the page level but can only be erased at the block level. In addition, with solid-state storage, cells must be erased before data can be rewritten to them. As a result, data and metadata is written multiple times, increasing the number of program/erase (P/E) cycles over the life of an SSD.
Write amplification is a problem because flash cells can handle only a finite number of P/E cycles before becoming unreliable. The extra P/E cycles involved in write amplification degrade the flash cells and reduce the lifespan of the device.
Question 5
Which problem is associated with the increased capacity of QLC technology, which is starting to show up in 3D NAND?
A. Decreased reliability
B. Slower response time
C. Lower endurance
D. All of the above
Answer
D. All of the above
Explanation
QLC NAND flash has higher capacity compared with MLC and TLC. However, QLC has its disadvantages.
For instance, the more bits in a memory cell, the fewer write cycles it can support before it begins to degrade. That makes it increasingly difficult to accurately read bit values. In addition, the increased bit count in QLC makes it slower. A single-level cell (SLC) drive takes about 1.5 to 2 milliseconds to erase a cell, while it’s estimated that a QLC drive has an erase time of more than 6 milliseconds.
QLC flash memory also wears out faster than other types of 3D NAND flash memory. SLC drives have an endurance rate of about 100,000 P/E cycles. MLC drives can handle about 3,000 P/E cycles and TLC drives about 1,000 write cycles. QLC drives are estimated to be able to endure only about 100 write cycles.
Question 6
Which new type of memory is a possible replacement for 3D NAND flash technology?
A. Planar NAND
B. Magnetic RAM
C. Static RAM
D. NOR flash memory
Answer
B. Magnetic RAM
Explanation
Magnetic RAM (MRAM) is one of several new memory technologies being developed as possible replacements for NAND flash. It’s non-volatile technology based on one-transistor cells similar to dynamic RAM. This magnetic technology is already in use for the manufacture of HDD heads and has been offered as stand-alone memory for the last five years. An embedded MRAM version is in development.
Cost is the main factor standing in the way of wider use of MRAM and some of the other new technologies. High costs are preventing them from being used anywhere except in niche applications for now.
Question 7
Which company doesn’t offer 3D NAND memory?
A. Toshiba
B. Yangtze Memory Technologies
C. Crossbar
D. SK hynix
Answer
C. Crossbar
Explanation
Toshiba, Yangtze Memory Technologies Co. (YMTC), SK hynix and others laid out plans for their next-gen 3D NAND flash technology and products at the 2018 Flash Memory Summit earlier this year. Toshiba launched a low-latency chip called XL-Flash. YMTC unveiled its Xtacking architecture that the company said is designed to increase performance and bit density. And SK hynix talked up its latest NAND flash technology that it’s calling 4D NAND.
Crossbar has developed a type of memory called Resistive RAM (ReRAM) as an alternative to NAND flash. ReRAM is non-volatile memory that operates by changing the resistance of a specially formulated solid dielectric material. Crossbar said its memory technology can be integrated into a memory chip or produced as a stand-alone chip.