Comparison Kingston NV2 SNV2S/250G 250 GB vs Kingston NV1 SNVS/250G 250 GB

Connection interface supported by an M.2 drive (see Form Factor).

All such drives use a standard hardware connector, however, different electrical (logical) interfaces can be implemented through this connector — either SATA (usually SATA 3), or PCI-E (most often in PCI-E 3.0 2x, PCI-E 3.0 4x, PCI-E 4.0 4x, PCI-E 5.0 4x). The M.2 connector on the motherboard must support the appropriate interface — otherwise the normal operation of the SSD will not be possible. Let's consider each option in more detail.

SATA 3 connectivity provides data transfer rates up to 5.9 Gbps (approx. 600 Mbps); it is considered a very simple option and is used mainly in low-cost M.2 modules. This is due to the fact that this interface was originally created for hard drives, and for faster SSD drives, its capabilities may no longer be enough.

In turn, the PCI-E interface provides higher connection speeds and allows the implementation of special technologies like NVMe (see below). The designation of such an interface indicates its version and the number of lines – for example, PCI-E 3.0 2x means version 3 with two data lines. By this designation you can determine the maximum connection speed: PCI-E version 3.0 gives just under 1 GBps per line, version 4.0 – twice as much (up to 2 GBps), 5.0 – twice as much a...s the “four” (almost 4 GBps). Thus, for example, for PCI-E 5.0 4x the maximum data transfer speed will be about 15 GBps (4 lanes of almost 4 GBps). However, we note that newer and faster drives can be connected to earlier and slower M.2 connectors – except that the data transfer speed will be limited by the capabilities of the connector.

Model of the controller installed in the SSD.

The controller is a control circuit, which, in fact, ensures the exchange of information between the memory cells and the computer to which the drive is connected. The capabilities of a particular SSD module (in particular, read and write speed) largely depend on this particular scheme. Knowing the controller model, you can find detailed data on it and evaluate the capabilities of the drive. For simple everyday use, this information is usually not needed, but for professionals and enthusiasts (modders, overclockers) it can come in handy.

Nowadays, high-end controllers are produced mainly under such brands: InnoGrit, Maxio, Phison, Realtek, Silicon Motion, Samsung.

The type of the main memory of the drive determines the features of the distribution of information over hardware cells and the physical features of the cells themselves.

— MLC. Multi Level Cell memory based on multi-level cells, each of which contains several signal levels. MLC memory cells store 2 bits of information. Has optimum indicators of reliability, power consumption and productivity. Until recently, the technology was popular in entry-level and mid-range SSD modules, now it is gradually being replaced by more advanced options in the manner of TLC or 3D MLC.

— TLC. The evolution of MLC technology. One Flash Memory Triple Level Cell can store 3 bits of information. Such a recording density somewhat increases the likelihood of errors compared to MLC, in addition, TLC memory is considered less durable. A positive feature of the nature of this technology is its affordable cost, and various design tricks can be used to improve reliability in SSDs with TLC memory.

— 3D NAND. In a 3D NAND structure, several layers of memory cells are arranged vertically, and interconnections are organized between them. This provides greater storage capacity without increasing the physical size of the drive and improves memory performance due to shorter connections for each memory cell. In SSD drives, 3D NAND memory can use MLC, TLC or QLC chips - more details...about them are described in the corresponding help paragraphs.

— 3D MLC NAND. MLC-memory has a multilayer structure — its cells are placed on the board not in one level, but in several "floors". As a result, manufacturers have achieved an increase in storage capacity without a noticeable increase in size. Also, 3D MLC NAND memory is characterized by higher reliability than the original MLC (see the relevant paragraph), at a lower manufacturing cost.

— 3D TLC NAND. "Three-dimensional" modification of the TLC technology (see the relevant paragraph) with the placement of memory cells on the board in several layers. This arrangement allows you to achieve higher capacity with smaller sizes of the drives themselves. In production, such memory is simpler and cheaper than a single-layer one.

— 3D QLC NAND. Quad Level Cell flash type with 4 bits of data in each cell. The technology is designed to make SSDs with large volumes widely available and finally retire traditional HDDs. In the 3D QLC NAND configuration, the memory is built according to a “multi-level” scheme with the placement of cells on the board in several layers. "Three-dimensional" structure reduces the cost of production of memory modules and allows you to increase the volume of drives without compromising their weight and size component.

— 3D XPoint. A fundamentally new type of memory, radically different from traditional NAND. In such drives, memory cells and selectors are located at the intersections of perpendicular rows of conductive tracks. The mechanism for recording information in cells is based on changing the resistance of the material without the use of transistors. 3D XPoint memory is simple and inexpensive to produce, and offers much better speed and durability. The prefix "3D" in the name of the technology says that the cells on the crystal are placed in several layers. The first generation of 3D XPoint received a two-layer structure and was made using a 20-nanometer process technology.

The highest speed in write mode characterizes the speed with which the module can receive information from a connected computer (or other external device). This speed is limited both by the connection interface (see "Connector"), and by the characteristics of the device of the SSD itself.

The highest data exchange rate with a computer (or other external device) that the drive can provide in read mode; in other words — the highest speed of information output from the drive to an external device. This speed is limited both by the connection interface (see "Connector"), and by the characteristics of the device of the SSD itself. Its values can vary from 100 – 500 MB / s in the slowest models to 3 Gb / s and higher in the most advanced ones.

A parameter that determines the resistance of the drive to drops and shocks during operation. Measured in G — units of overload, 1 G corresponds to the usual force of gravity. The higher the G number, the more resistant the device is to various kinds of shocks and the less likely it is to damage the data in it, say, in the event of a fall. This parameter is especially important for external drives (see Type).

The drive's time between failures is the time that it is able to continuously work without failures and malfunctions; in other words — the operating time, after which there is a high probability of failures, and even failure of the module.

Usually, the characteristics indicate some average time derived from the results of conditional testing. Therefore, the actual value of this parameter may differ from the claimed one in one direction or another; however, in fact, this moment is not particularly significant. The fact is that for modern SSDs, the MTBF is estimated at millions of hours, and 1 million hours corresponds to more than 110 years — while we are talking about pure operating time. So, from a practical point of view, the durability of a drive is often limited by more specific parameters — TBW and DPWD (see below); and the manufacturer's warranty generally does not exceed several years. However, data on the MTBF in hours can also be useful when choosing: other things being equal, more time means more reliability and durability of the SSD as a whole.

The abbreviation TBW stands for drive time between failures, expressed in terabytes. In other words, this is the total amount of information that is guaranteed to be written (rewritten) to this module. This metric measures the overall reliability and lifespan of a drive—the higher the TBW, the longer the device will last, all other things being equal.

Note that knowing the TBW and the warranty period, you can calculate the number of rewrites per day (DWPD, see the relevant paragraph), if the manufacturer did not specify these data. To do this, use the formula: DWPD = TBW / (V * T * 365), where V is the drive capacity in terabytes, T is the warranty period (years). As for specific numbers, there are a lot of drives on the market with a relatively low TBW — up to 100 TB ; even these values are often sufficient for everyday use for a considerable amount of time. However, models with TBW at the level of 100 – 500 TB are more common. Values of 500 – 1000 TB can be classified as "above average", and in the most reliable solutions this figure is even higher.

Module support for the TRIM command.

A feature of the operation of SSD modules is that when deleting data in the normal mode (without using TRIM), changes are made only to the “table of contents” of the drive: certain cells are marked as empty and ready for new information to be written. However, the old information is not deleted from them, and when writing new data, you actually have to overwrite it — this significantly slows down the speed of work. The TRIM command is designed to correct the situation: when it arrives, the drive controller checks if the cells marked as empty are empty and cleans them if necessary.

Of course, this function must be supported not only by the drive, but also by the system, however, the ability to work with TRIM is built into most popular modern operating systems.