When consumers buy SSDs, they will always study their durability and life. After all, it is really troublesome for the hard disk to hang up, and all the data in it will be lost. However, for a single hard disk, it is impossible to predict its life. Whether mechanical hard disk or solid-state hard disk, they are a Schrodinger time bomb and may explode at any time, The probability will increase over time, and your lucky value and power stability will become dynamic variables to affect this result.

For a product group, the approximate average life can be predicted. When it comes to the life of SSD, first of all, you will think of the limit on the number of writes of flash memory, which is related to the working principle of flash memory. Taking the floating gate NAND flash memory as an example, whether the flash memory is powered on or not represents the 1 and 0 states recognized by the computer, At the moment of power on, a strong electric field (more than 10 million VT / cm) will be generated. Such a strong electric field will destroy the atomic bonding of the tunnel oxide layer, and the separated electrons will rise to the floating gate to form a potential change. After power off, the electrons will return to their normal position. In this way, repeated power off pressurization will form different potential signals.

The power on process is equivalent to the data writing operation of HDD Hard disk, which is called “program”. The potential recovery during power off is equivalent to the erasing data of HDD Hard disk, which is called “erase”. A complete P / E cycle is the NAND writing cycle. It can also be seen that if SSD wants to write data, it needs to restore the default potential, That is, on the premise of “erasure”, this feature determines the data writing mode of SSD, which will also bring a series of other problems.

With the P / E times of flash memory and the capacity of SSD, the maximum life of SSD under ideal conditions can be calculated through a formula: SSD life = (flash memory P / E) × SSD flash memory capacity) ÷ (write amplification factor) × Annual data writes).

Take a 240gb 3D TLC SSD as an example. The flash memory is 3000P / e. the flash memory capacity of the SSD is actually 256gb. The write amplification factor is actually related to the main control algorithm and the type of data written. In fact, it is difficult to say the specific value. Here, take 5 as a larger value. As for the annual data write volume, it completely depends on personal usage habits. Here, take 2000gb, In fact, the write volume is quite large, so: (3000) × 256)÷(5 × 2000) = 76.8 years.

Can this SSD last 76 years? The theoretical life of flash memory is correct. However, as I said just now, this is the maximum life of the theory, which is calculated under the ideal situation, and what is its minimum value? In fact, you can refer to the warranty market provided by manufacturers for SSDs, most of which are three or five years. Some high-end products will provide a ten-year warranty. They give such a warranty time, which shows that this SSD has a high probability that it will not break down during this period. After all, RMA requires human and material resources. If SSDs die in a large area during the warranty period, the manufacturers will lose a lot of money, And it’s not good for your reputation.

In addition, most manufacturers also give the life cycle write amount TBW of SSDs, and some give the daily replication times dwpd, which can actually be converted into TBW. Assuming that the manufacturer gives a dwpd of 1 for a 512gb SSD, it shows that it can write its own data once a day, that is, 512gb, and the warranty period is 5 years, so its TBW is equal to 512gb × three hundred and sixty-five × 5 ÷ 1024=912.5。

Some people mistakenly think that this TBW is the total amount of data that can be written in the SSD life cycle. After writing so much data, the SSD will hang up. In fact, it is not. In fact, this number means that if you write more than so much data during the warranty period, you will not be guaranteed, because your writing operation has exceeded the scope of the normal use of the SSD, In fact, generally speaking, this number is also very difficult to exceed. For those who can exceed this number, I really want to know how you usually torture this SSD.

Another possibility is that the main controller and flash memory are all safe, but other power supply components are broken. Although everyone only cares about the main chips of the main controller, flash memory and cache on the SSD, there are actually many other chips and components on it, and these things may also fail. In case of failure, the whole SSD may be paralyzed, Especially when the power supply is unstable, the power supply components are quite likely to be burned. However, in fact, SSD data may be saved, and the data is really gone when flash memory or master control hangs up.

So there’s nothing to be afraid of. Whether the SSD dies suddenly is actually a dice roll. If you’re unlucky, you’ll die. Instead of worrying about the life of the SSD, you’d better buy a good performance one to use it better. If you’re really worried, you can buy one with longer quality assurance. At least, the possibility of SSD dying during the warranty period is relatively small.

Finally, there are two common death methods for SSDs. The first is write locking, that is, the master checks that your SSD is no longer working and is not allowed to write anything directly. This is actually the best way to die. At least you have the opportunity to save data, and the second is sudden death without warning. This is actually the most common, You don’t have any chance to save your data, and manufacturers won’t help you recover your data in most cases. If you find a third-party data recovery service, the price is also very high, so back up your important data.