SSDs are totally different when it comes to working than HDDs and although their purpose is the same, their pros and cons, as well as the techniques they use, usually have nothing to do with it. In SSD a series of specific algorithms are needed to take care of certain tasks and to allow it to be properly maintained, even prolonging its useful life. This is precisely what Wear Leveling takes care of, but how does it do it?
It all starts from where and how the information is stored in an SSD with respect to an HDD. As we know, the latter uses various magnetic plates that, through various techniques, record the data on its surface, magnetically polarizing them into zeros or ones.
An SSD stores the information on NAND Flash chips and therefore suffers from degradation over time, something that would be really worrying if it weren’t for our protagonist.
SSD Wear Leveling, this is how your SSD prolongs its useful life
The biggest problem with SSDs is increasing capacity without decreasing their lifespan, gaining performance with it. Due to the nature of this type of device, the blocks of the NAND Flash with the passing of the cycles tend to fail after the corresponding deletions and writes.
This happens every day without exception and it is normal that the controller at some point go directly to write to one of these blocks that have to be reassigned. To prevent this from happening, controllers have an algorithm that handles this task efficiently, so that data is not lost or corrupted. It is called Wear Leveling or wear leveling algorithm.
As a general rule, the controller of an SSD will not write to an already active block, but will spread the information over different blocks in order to precisely level its wear. But, although this fact is perfected, the truth is that at a higher speed a greater number of possible failures appear and a better Wear Leveling algorithm is increasingly necessary .
Two types of wear leveling algorithms
We start from the basis that there are three types of blocks:
- Those who undergo changes .
- Those that are not being used.
- The ones that are static with data.
Knowing this, manufacturers work with two types of leveling algorithms: static and dynamic. The static-based algorithm handles writing to all blocks on the SSD, which means that those that are static with valid data will move to allow all blocks to receive the same amount of wear.
The dynamic algorithm only uses the blocks that are not used and those that undergo changes, this allows those that are static to not suffer any wear and level the balance with the other two types.
Although the two algorithms work differently, in both cases it is estimated where the data will move, how much it will move and how fragments can be consolidated to make complete blocks. Logically this can suppose an overwriting if it is not done well and achieve the opposite effect to what is intended.
What is the impact of these algorithms on the life of the SSD? Well, it all depends on the algorithm and the precision that the manufacturer has. This algorithm works in line with others such as garbage collection and also partly determines the performance of the SSD itself.
If you do your job really well and match block wear, you can extend the life of your block by almost three times compared to not including it on the SSD.
