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I think a lot of people know that SSDs don't last very long. Of course, this is a conclusion compared to mechanical hard drives, and they can indeed be used for a long time. So what affects lifespan of an SSD? Today I'm just going to show you real reason why SSDs don't last long.

Number of erasures

The erasing and writing times of SSDs are fixed, so their lifetime is limited. One erase and write is called 1 P/E, so lifetime of SSDs is based on P/E and usually does not use time as a unit.

So what counts as a wipe? Does copying a file count? The so-called one-time erase and write, for example, such as a 100G solid state hard disk, you fill it with all data, and then erase it all, this is considered a one-time erase and write, one file is copied and deleted, it does not count at one time.

How to calculate life expectancy

SSD lifespan is determined by following formula: year = (actual GB capacity × P/E time) ÷ (daily GB write capacity × 365)

For example, an SSD has a P/E of 100, an actual capacity of 10 GB, and writes 1 GB every day. How long can it be used? That is: (10×100)÷(1×365)≈2.74 years

10GB SSD can be used 2.74 years, then 100GB is decades, of course it's not possible, because that's a theoretical life, that's our topic today, an important factor that really affects life of an SSD is "Write amplification ".

Amplify Recording

What is write amplification? Write amplification means that amount of physical data actually recorded is N times amount of recorded data. Therefore, here we will not explain in detail how an SSD is written and erased, we will give a popular example for clarification.

For example, a box (SSD) can hold four apples (data), and now there are three apples in it, so I want to put (write) another apple (data), how to put it at that time ? That's right, it can indeed be inserted directly (write), but that's not what an SSD does. It will first take out three apples (erase) and then put four apples together (write). know if everyone can understand it.

Although we are writing part of data to solid state hard drive, solid state hard drive will erase part of original data, pull it out and write part we want to write, that is, solid state drive writes The actual amount of data entered is much more than what we gave it . To give an unsubstantiated example, you are obviously writing 1 GB of data to SSD, but SSD is actually writing 10 GB.

This is real reason why lifetime of SSDs is completely different from theoretical lifetime.

So how do you avoid recording amplification? This cannot be changed. The only thing we can do is reduce damage caused by write amplification, and way to significantly reduce impact of write amplification is to use a higher grade solid state master disk. However, from this point of view, choice of main controller of SSD is very important, so when buying an SSD, try to choose products that use main controllers of first line (Samsung, Intel, Toshiba, etc.).