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What Is SSD Wear Leveling And Why It’s Important?

    I have been telling you the importance of SSDs since our first article. But there are many things regarding SSDs that you need to know.  Since SSDs have been known to have limited yet long lifespans but it totally depends upon you that how efficiently you use your SSD.

    The main factors that affect the life of an SSD are the grade of flash used, age, Physical damage, and heat. We all know that SSDs don’t heat that much as compared to HDDs but it still matters. Single Level Cell SSDs have the largest lifespan followed by MLC and TLC SSDs.

    Wear leveling is responsible for the long lifespan of data stored on an SSD.  Wear Leveling algorithms are properly distributed over SSD blocks so that the block doesn’t wear out before expected. This article is going to be all about wear leveling and its importance in SSDs. We will be discussing types of wear leveling and the main concepts regarding that.

    What Is Wear Leveling In SSDs?

    Before Knowing more about wear leveling we should know that what causes wear out in SSDs. Frequent writing and rewriting the same memory point causes wear out that particular portion of memory block making it invalid.

    With the passage of time, all memory points can wear out. This is where Wear leveling comes into play. The main function of wearing level is to extend the life span of SSD. Wear leveling comprises a set of algorithms deployed on physical blocks of SSD. 

    In general wear, leveling can be done on all kinds of erasable storage devices for their prolonged life span. The mechanism of wear leveling allows evenly wear out of memory blocks. It helps in avoiding the overuse of memory blocks so that every block can be used to the maximum extent.

    Different Types Of Wear Levelling In SSDs(Solid State Drives)

    There are many Wear Leveling algorithms for SSDs but out of all of the two are main. The three main types of Wear leveling in SSDs are:

    • Dynamic Wear leveling
    • Static Wear leveling

    To have a further understanding of these wear-leveling algorithms I will explain to you all these separately.

    Dynamic Wear Leveling

    Dynamic Wear leveling ensures that data is written on the blocks that have undergone the lowest erase count. This wear-leveling algorithm works only on blocks or areas that are not constantly modified in order to create a balance. As a result, the blocks which are rarely used don’t come under Dynamic wear leveling. 

    The working of Dynamic wear leveling includes the track of no. of write cycles underwent by a specific memory block. The write cycle count of a new SSD is zero and it increases by one every write cycle. 

    Since wear leveling can be done only on the Non-static part of data this is the most efficient method for dynamic data. A flash drive system that has dynamic wear-leveling experiences a longer life span than others.

    If an SSD has 30% of dynamic stand and 70% of static data then Dynamic wear leveling hits only 30% whereas the other 70% of memory blocks with static data remain untouched. As a result, 30% of the memory blocks with dynamic data are utilized up to their maximum cycle count.

    Static Wear Leveling

    In static wear leveling, all the good blocks are utilized to distribute the wear evenly. This wear leveling mechanism keeps the track of cycle count of all the good blocks and evenly distributes the wear throughout the entire memory blocks by selecting the blocks with the least count of wear on each execution of the program.

    Usually, static data has a threshold of erase count. The memory blocks that start lagging due to erasing count are included in the wear-leveling blocks pool with their static data moved to blocks with higher erase counts. Static wear leveling is considered the best method to increase the lifespan of SSDs. 

    A normal MLC SSD with an erase rate of 40 blocks per 10 minutes can increase the lifespan of an SSD by 15 years. 

    Difference Between Dynamic And Static Wear Leveling

    Dynamic Wear LevellingStatic Wear Leveling
    Improves device life over no wear leveling at allMaximizes device life 
    May Or May not optimize device lifeSlows WRITE operations 
    Zero effect on device performanceHigh power consumption
    It is quite easy to implement than static wear levelingMore complicated to implement as compared to dynamic wear leveling
    comparison table (dynamic vs static wear leveling)

    Importance Of Wear Leveling In SSDs

    The continuous use of the same memory blocks every time exceeds the endurance of those blocks resulting in reducing the span of SSD life. To enhance the finite P/E(Program/Erase) cycles of NAND flash memory cells Wear leveling is required. In Nutshell, Wear Leveling is important to equalize the use of all memory cells to extend the life of an SSD. In the absence of wear leveling the storage cells of flash storage devoice are not used efficiently. So, Wear Leveling not only increases the life of an SSD but also enables a justified usage of all storage blocks of the device. 

    Let us see through an example:

    If an SSD has 4096 memory blocks with 2.5% of allowable bad blocks that update 3 files of 50 blocks at the rate of 1 file in 10 minutes and an SSD reuses the same memory blocks for these updates resulting in wear out in a time of less than a year with more than 95% of memory blocks unused. 

    Now Contrary to the first case

    In an SSD all the 4096 blocks are equally P/E at a rate of 50 memory blocks per 10 minutes then wear among all the memory blocks will be evenly distributed thus technically increasing the lifespan of the device.

    How to check Wear Level And Health Of Your SSD

    Here are some applications that will help you in knowing the wear level of your SSD. 

    1. Hardware Monitor(For Windows)

    Download hardware monitor application

    Open the application and locate your SSD

    SSD Reporter(MAC)

    You can Install the SSD Reporter utility

    Run the application And Check the status of your SSD. this application has a color indicator for the health of your SSD. Green means Safe, Yellow for Warning, and Red for Errors

    The Conclusion

    Wear leveling is not common among SSDs only but is also done in other-flash storage devices such as Pendrive etc for effective use. You can check the wear level and life expectancy of your SSD from the applications mentioned above.

    Also, Reading of data doesn’t cause any wear in SSDs. Wearing of SSDs is caused by Reading and deleting cycles. In case you have any doubts regarding the same then do tell me in the comment section. I will be there for you.


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