Tech Explained – Samsung 3D V-NAND. What is a v nand ssd

This is achieved by constructing a conductive mold stack of 136 layers and then perpendicularly engaging the cylindrical openings from top to bottom. In this way, uniform 3D cells with a cargo trap (CTF.

Storage 101: Understanding the NAND Flash Solid State Drive

Today, most organizations use SSDs for everything from laptops to enterprise database storage and virtual machines. In this article, Robert Sheldon explains how NAND flash SSDs work.

Previous series:

Solid state drives (SSDs) have made a significant step into enterprise data centers in recent years, handling workloads that were once the exclusive domain of hard drives (HDDs). SSDs are faster, smaller, use less power, and have no moving parts. They also fell in price while supporting higher densities, making them suitable for a wide range of applications.

Despite their growing presence in the enterprise, there is still a lot of confusion about how SSDs work and the features that distinguish one drive from another. Concepts like NAND chips, multi-level cells, and floating gate technologies can be a bit daunting if you still think in terms of spinning disks and movable actuator arms, components that don’t have room for an SSD.

The more you understand how SSDs work, the more efficiently you can select, deploy, and manage them in your organization. To assist with this process, this article introduces some important concepts of SSDs so that you get a clearer picture of the components that make up an SSD and how they work together to provide reliable persistent memory.

However, keep in mind that an SSD is a complex technology and can easily justify a much deeper coverage than what a single article can offer. You should think of this as an introduction, not a complete treatise, a starting point for building the foundations for understanding the inner workings of your SSDs.

Introducing the NAND Flash SSD

Like a hard disk, an SSD is a non-volatile storage device that stores data whether or not it is connected to power. However, a hard drive uses magnetic media to store data, while an SSD uses integrated electronic circuits to preserve certain states of charge which, in turn, map to data bit patterns.

SSDs are based on flash memory technologies that allow data to be written, read, and erased multiple times. Flash memory comes in two varieties: NOR and NAND. While each has its own advantages and disadvantages (a discussion that is beyond the scope of this article), NAND has become a favorite technology as it provides faster erasing and writing. Most modern SSDs are based on NAND flash memory, which is why this is what this article focuses on.

An enterprise SSD contains multiple NAND flash memory chips for data storage. Each token contains one or more cubes, and each cube contains one or more planes. The plane is divided into blocks and the block is divided into pages.

Of these, the biggest problem is blocks and pages, not because you configure them directly or manipulate them directly, but because of the way data is written, read, and deleted on the NAND chip. Data is read and written at the page level but deleted at the block level as shown in Figure 1.

Figure 1. Saving and erasing data on a NAND flash SSD drive (photo by Dmitry Nosachev, under the Creative Commons Attribution-Share Alike 4.0 International license)

In this case, each page is 4 KibiBytes (KiB) and each block is 256 KiB, which is equivalent to 64 pages per block. (Kibibyte is 1024 bytes. Kibibytes are sometimes used instead of kilobytes because they are more precise. A kilobyte can be 1000 bytes or 1024 bytes depending on its use.) Every time an SSD reads or writes data, it does so in Pieces 4 KB, but each time the disk erases data it performs a 256 KB operation. This difference between save and erase has serious ramifications when updating data, as you’ll see later in this article.

Most client systems are no longer limited by CPU performance. They are almost always limited by storage. Hard drives have access latency in milliseconds while SSDs run in hundreds of microseconds.

A New Way To Increase Capacity – 3D V-NAND

3D V-NAND is a cell layering technology where multiple layers are created on a single NAND chip. Samsung implements up to 32 layers for chips that go to the latest SSDs. Note that cells are stacked, not the chips themselves. Of course, more layers means potentially more storage capacity. V-NAND is great because it works on top of existing manufacturing processes such as the 10nm plus class, helping to alleviate the problems of reduced endurance and inferior performance when NAND is further scaled.

This is an important point. As memory cells shrink as a result of moving to smaller manufacturing processes, lower operating voltages and more cells can be expected to fit in a given area, thus increasing the capacity per chip, which is crucial in the quest for SSD capacity over 1 TB. While this is reasonably true, ever smaller processes – where cells are very, very close to each other – have a huge side effect: disruption. The proximity of the cells causes disturbances that inhibit the speed of the entire chip. So, while smaller manufacturing processes are generally a good thing, they also have undesirable problems. 3D V-NAND takes advantage of many of the advantages of low-volume chips, but not the disadvantages.

In addition, switching to the 3D vertical cell stacking model means that compared to regular “flat” flat NANDs, Samsung’s 3D V-NAND requires less physical space for the same capacity – remember that multiple layers of cells are stacked on top of each other – thus enables mature production processes to be used instead.

Reinventing The NAND Chip

3D V-NAND is about more than just stacking more layers on a chip. Flash memory uses an electrically insulated gate floating beneath the transistor’s control gate – CPU transistors only have one gate – and its purpose is to increase the voltage threshold needed to make the transistor conductive. When a load enters the float gate through the control gate, the memory is said to be programmed. Removal of the load causes the content to be deleted.

Instead of using a traditional floating gate to add or remove charge coming from a control gate, Samsung says, which is extremely difficult when building a 3D device, it is replaced by a charge trap, which is a non-conductive layer that effectively wraps around the transistor. This layer is critical in minimizing inter-cell interference, has less leakage properties, requires less voltage to operate, and therefore uses less energy. A byproduct of the lower tension is less stress and increased strength than would be possible with a conventional floating gate.

Samsung took a look at the technology behind the chips that make up SSD capacity and devised a method to increase capacity, reduce power consumption, and increase overall endurance without having to follow an expensive, problematic pathway to a smaller manufacturing process. The transition to 10nm and smaller will take place in due course, but Samsung thinks it makes more sense to use mature processes to minimize risk and keep the NAND chips flowing from the factories. Taken together, these enviable features enable Samsung to offer class-leading performance and power consumption on the latest SSD array for consumers and data centers.

One of the benefits of NAND flash memory is non-volatile data storage. Unlike DRAM, which must be powered continuously to retain data, NAND memory retains data even when powered off – making it ideal for storing portable devices.


Samsung SATA 256GB SSD using 6th generation V-NAND technology.

Details of 250GB V6 SATA SSD:

  • 136 layers of flash cells with charging trap
  • Single stack design
  • 512Gbit matrix
  • TLC (3 bits / cell)
  • reading delay 45 μs
  • 450 μs write delay
  • SATA 12Gbit / s interface

Samsung said it produced the 1xx die with 670 million channel holes, compared to the more than 930 million needed for the V5 9x generation. This improved production efficiency by more than 20 percent. The die is also 10 percent faster at IO than the 9x product and consumes 15 percent less energy.

Layer count transitions

Samsung said it introduced the V6 1xx layer technology 13 months after the introduction of the V5 9x. That’s four months faster than the transition from the 64 V4 layers to the V5 9x.

Kye Hyun Kyung, Vice President of Product and Solution Development, Samsung Electronics, said: “With faster next-generation V-NAND product development cycles, we plan to rapidly expand our markets for our high-speed and capacious 512Gb solution-driven V-NAND.”

This means that V7 200+ layering technology will debut in September 2020, V8 3xx technology in October 2021, V9 4xx technology in November 2022, and V10 5xx technology in December 2023, assuming 13- a monthly transition period.

SK hynix suggested that it would roll out its 500-layer technology in 2025, giving Samsung a one-to-two lead.

Today, most organizations use SSDs for everything from laptops to enterprise database storage and virtual machines. In this article, Robert Sheldon explains how NAND flash SSDs work.

NAND Flash Technology and Solid-State Drives (SSDs)

If you own a Kingston USB flash drive or SD card, you already have products that include flash memory, also known as NAND flash. Worldwide, NAND flash memory consumption has accelerated rapidly in the past five years, and new products such as SSDs are now entering the market for enterprise computing devices such as notebooks, desktops, workstations, and servers.

Here’s a quick rundown of what you need to know about NAND Flash.

Non-Volatile NAND Flash Memory

One of the benefits of NAND flash memory is non-volatile data storage. Unlike DRAM, which must be powered continuously to retain data, NAND memory retains data even when powered off – making it ideal for storing portable devices.

M.2 and mSATA SSDs

Types of NAND Flash

There are currently five types of NAND flash, and the difference between each is in the number of bits each cell can store. Each cell can store data – one bit per cell for SLC NAND, two bits per cell for MLC, three bits per cell for TLC, four bits per cell for QLC, and five bits per cell for PLC. Thus, SLC NAND stores “0” or “1” in each cell, MLC NAND stores “00”, “01”, “10” or “11” in each cell, and so on. These five types of NAND memory offer different levels of performance and endurance at different price points, with SLC being the more efficient and most costly NAND on the market.


In 3D NAND, multiple layers of memory cells are arranged vertically along with connections between the layers. Stacking multiple layers of memory cells into vertical tiers provides greater storage capacity while taking up less space and increasing performance by allowing shorter connections for each memory cell. It also lowers the cost per byte compared to 2D NAND. 3D NAND flash devices can use MLC, TLC or QLC designs.

SATA SSD in a server chassis half pulled from the server's storage bay

NAND Cell Wear Leveling

NAND cells are not designed to last forever. Unlike DRAMs, their cells will wear out over time because the write cycles are more strenuous than the read cycles. NAND storage devices have a limited number of write cycles, but wear leveling manages the cell usage realized by the flash controller, which is always on the device. All USB flash drives, SD cards, and SSDs are equipped with a NAND controller that manages the NAND flash memory and performs functions such as wear-leveling and error correction.

To extend the life of NAND storage devices, the NAND Flash controller ensures that all recorded data is evenly distributed over all physical blocks of the device so as not to consume one area of ​​NAND storage faster than another.

Solid-State Drives (SSDs)

Over the past few years, the cost of NAND flash has fallen so much that new core storage devices such as solid-state drives have become available for client systems and servers. SSDs are direct replacements for hard drives (or standard rotating hard drives) in computers with compatible interfaces such as SATA or SAS.

SSD drives offer significant performance and endurance advantages over standard hard drives. SSDs have no moving parts; they are all semiconductor devices. For this reason, SSDs are not subject to the mechanical delay that hard drives do, and without moving parts, SSDs can be subjected to much greater shock and vibration than a hard drive, making them ideal for a wide variety of portable and mobile applications.

SSD configurations can vary greatly from one one to another, so don’t assume others will look like an HGST drive. I chose this one because it makes a good example of a NAND flash SSD.


If you look back before 2015, the story shows that there is no difference between 3D NAND and V-NAND, and that they both refer to the same thing.

It’s just that the former has a bit more “3D” in it. The term V-NAND or 3D Vertical NAND simply refers to the fact that NAND cells are arranged vertically to take advantage of the three-dimensional nature of space. Both refer to NAND memories that are stacked vertically on top of each other.

As you know, V-NAND is the marketing term of 3D NAND introduced by Samsung in 2013, when they were the first to put functional 3D NAND cells on their devices, which means the end of the price war for SSD drives.

This was a decisive milestone in the development of high-speed storage devices as vertical cell stacking allowed for more storage at a lower cost, which has brought the benefits we experience today.

Even the cheapest SSDs can now come in capacities up to 2TB, allowing users to build PCs with fast and reliable storage.

3D V-NAND SSD Technology

Multiple layers of flash memory cells are layered vertically and three-dimensionally on a single NAND chip in V-NAND, also known as 3D V-NAND. The chips in question have 36, 48, 72, 64, and now 96 layers of flash cells arranged vertically.

The technique uses either 3D flash cargo trap (CTF) cells with vertical channel openings built in a pyramid or stair tread structure, or the more traditional floating gate MOSFET technology.

Vertical stacking allows for a higher cell density per volume than a 2D design. One word of explanation: the layers of cells are stacked, not the chips themselves.

As a result, we can have SSDs with greater capacity without having to increase the RAM.

It also reduces the amount of energy used by connected memory cells. It allows the production of more efficient SSDs with increased capacity.

All of this is done without suffering the typical adverse effects of NAND lithography, which are reduced to fewer process nodes such as noise, durability and performance.

Modern SSDs Are Vertically Stacked

All SSD manufacturers now use vertical stacking, mainly due to the performance associated with 3D NAND memory. It allows both producers and end users to have greater storage capacity at lower costs.

SSD prices vary, some are cheaper than others, but this is due to the type of NAND cell used; some varieties are more efficient at reading and writing, but are more expensive.

The truth is, it’s the best SSD in terms of use and price range, but it’s not the best SSD overall. Vertically stacked SSDs increase memory capacity, but performance and reliability suffer from more bits per NAND cell.

How can flash NAND, specifically V-NAND vs. 3D NAND, with so many names for different terms? Here are some explanations to help you better understand NAND, especially 3D NAND vs. V-NAND.

DRAM Cache

Each time the system instructs the SSD to retrieve some data, the drive needs to know exactly where the data is stored in the memory cells. For this reason, the disk stores a kind of “map” that actively keeps track of where all the data is physically stored. This “map” is stored in the disk’s DRAM cache. This cache is a separate, high-speed memory chip inside an SSD, which can often make a big difference. This form of memory is much faster than the separate NAND flash memory inside an SSD.

Importance of DRAM Cache

A DRAM cache can be important in more ways than just storing a data map. SSD drives quite a lot of data, trying to extend its life. This technique is called “Wear Leveling” and is used to prevent certain memory cells from wearing out too quickly. The DRAM cache can be of great help in this process. DRAM cache can also improve the overall speed of a disk as the operating system would not have to wait that long to locate the requested data on the disk. This can greatly improve performance in “Operating System Disks” where there are many small operations that are performed very quickly. SSDs without DRAM also provide significantly worse performance in R / W random scenarios. Typical tasks.

Host Memory Buffer (HMB) Technique

We know that SSDs without an internal DRAM cache are flooding the market as cheaper alternatives, but offer inferior performance to SSDs that contain a DRAM cache. However, SSDs without DRAM are not limited to cheap 2.5-inch SATA SSDs, and many mid-range NVMe SSDs also lack internal DRAM cache. This is where the Host Memory Buffer or HMB technique comes into play.

NVMe disks communicate with the motherboard via the PCIe interface. One of the advantages of this interface over SATA is that it allows the disk to access the system RAM and use some of it as its own DRAM cache. This is what HMB drives achieve. These NVMe drives compensate for the lack of cache by using a small portion of the system RAM as the DRAM cache. It alleviates many of the performance drawbacks of blank SSDs without DRAM. It can also be cheaper than NVMe drives that contain a built-in DRAM cache.

DRAM and HMB cache. Note the CPU’s DRAM contribution to the HMB process – Photo: Kioxia


Surely cheaper drives won’t just be able to use your system RAM as a cache? While there are certainly advantages to using the HMB technique over simply not using the cache at all, the level of performance still doesn’t match cache drives. HMB offers somewhat intermediate performance. Improved random read and write performance compared to SSDs without DRAM memory, and improved overall system responsiveness, but not to drives with built-in cache. It all comes down to a trade-off in cost or performance. Check out our list of the best NVMe SSD brands to make your own choice.

Note that since HMB uses the NVMe protocol over PCI Express, it cannot be used on traditional SATA SSDs.


There is no doubt that if you are looking for the absolute best performance, you shouldn’t buy an SSD without a DRAM cache. While HMB can be useful in improving performance, there are still trade-offs with such workarounds. However, if you’re looking for a valuable NVMe SSD, some of the options that offer HMB features may be attractive compared to other DRAM cache drives. Especially when you use an SSD as a secondary drive, the performance degradation may not be as significant as the savings. In most cases, purchasing a SATA SSD without DRAM should be avoided.

However, not all SSDs are created equal. Consisting of a controller and NAND flash memory, only the largest companies can devote enough resources to research and development to drive the SSD market with true innovation.

The Groundbreaking Design of Samsung’s Sixth-Generation V-NAND SSD

3D memory takes it to a new level as 6th Generation V-NAND SSDs take advantage of Samsung’s unique manufacturing advantage. Samsung V-NAND 6th generation SSDs provide the fastest data transfer in the industry.

The new V-NAND SSD increases the cell count of the previous 9-fold single-layer structure by approximately 40% thanks to Samsung’s unique channel hole etching technology.

Samsung SSD

This is achieved by constructing a conductive mold stack of 136 layers and then perpendicularly engaging the cylindrical openings from top to bottom. In this way, uniform 3D cells with a cargo trap (CTF.

NAND flash chips are often more prone to errors and read lag as the height of the mold stack in each area of ​​the cell increases.

To overcome these limitations, Samsung has adopted a design optimized for speed. It achieves the fastest data transfer speeds – write speeds below 450 microseconds (μs) and read speeds below 45 μs.

Compared to the previous generation, the power consumption of the 6th generation V-NAND SSDs has been reduced by more than 15%, and the performance has increased by more than 10%.

Thanks to this speed-optimized design, Samsung can install three current stacks without affecting the performance or reliability of the chip, to provide over 300 layered next-generation V-NAND solutions.

In addition, the number of channel holes required to create the 256 Gb chip density has been reduced by 260 million (from over 930 million to 670 million). At the same time, it reduces chip size and process steps, which increases production efficiency by more than 20%.

To better meet customer demands around the world, Samsung is deciding next year to expand production of sixth-generation V-NAND solutions with greater capacity and speed at the Pyeongtaek (Korea.

This is the Samsung V-NAND Mass Production Timeline Reference Chart:

samsung V-NAND mass production timeline reference table

toshiba Western Digital 128-layer 3D Nand Mini Memory

Apparently, Toshiba and Western Digital are preparing 128-layer 3D NAND memory, offering greater capacity and higher performance.

Final Words

Samsung plans not only to expand its 3D V-NAND technology from the consumer space to next-generation enterprise servers, automotive markets and mobile devices by improving the performance and efficiency of sixth-generation V-NAND flash memory, but also plans to produce a 512Gb triple-bit V-NAND SSD and eUFS this year after today’s 250 GB SSD drive.

Position: Publicist

She completed a specialization in English. She has been the editor of MiniTool since she graduated from college. Specializes in writing articles on data and system backup, disk cloning, file synchronization, etc. She is also good at writing articles on computer knowledge and computer problems. On a daily basis, he enjoys running and going to the amusement park with his friends to play some exciting items.

Rate article