Size
Nominal drive capacity. This parameter directly determines not only the amount of data that can fit on the device, but also its cost; many SSD models even come in several versions that differ in capacity. Therefore, when choosing, it is worth considering the real needs and features of the application — otherwise you can overpay a significant amount for volumes that are not needed in fact.
In terms of actual values, a capacity of
120 GB or less is considered small these days. This can also be equated with
a 240 GB SSD. Average values are already considered
500 GB, increased —
1 TB(in the range of which
SSDs fall 400 and
800 GB). And the most capacious modern SSDs can accommodate
2 TB,
4 TB and
even more.
Controller
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.
Cache memory
Buffer memory is a small chip on the SSD drive that acts as a data transit between the drive and the motherboard. In fact, it acts as a kind of intermediate link between the computer's RAM and the drive's own permanent memory. The buffer is used to store the most frequently requested data from the module, which reduces the access time to them — the information is sent from the cache, instead of being read from the magnetic media. Usually, the larger the buffer size, the higher the speed of the drive, all other things being equal. Also, drives with a large amount of buffer memory reduce the load on the processor.
Read speed
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.
TBW
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.
DWPD
The number of full overwrites per day allowed by the design of the drive, in other words, how many times a day the entire drive can be guaranteed to be overwritten without fear of failures.
This parameter describes the overall reliability and durability of the drive. It is similar in meaning to TBW (see the relevant paragraph), one value can even be converted to another, knowing the warranty period: TBW = DWPD*V*T*365, where V is the drive capacity in terabytes, and T is the warranty period in years . However, DWPD is somewhat more specific: it describes not only the total time between failures, but also the limit on the number of rewrites per day; if this limit is exceeded, the drive may fail earlier than specified in the warranty. However, even small DWPD values —
0.5 – 1 time per day, or even
less than 0.5 times a day — often turn out to be sufficient not only for simple everyday use, but even for professional tasks. Higher rates —
1 – 2 times a day or
more — are rare; at the same time, it can be both high-end and low-cost SSD modules.
