Wear levelling prolongs your SSD’s lifespan – here’s how

We’ve recently written about how SSDs work and how, due to their lack of moving parts, they are far less likely to suffer from mechanical faults than HDDs as well as offer faster read/write speeds.

Lower costs aside, it would seem that HDDs have no real advantages over flash-based media, but this is not entirely true: as the cells of devices that utilise flash technology can only be adjusted (to either prevent or allow an electrical current to flow through them) a set number of times, all such devices have a finite lifespan. Alternatively, each small sector of a HDD can be magnetised and de-magnetised indefinitely.

This is unlikely to be an issue for the majority of non-commercial adopters, however. Drive’s cells can be adjusted multiple times before they fail and, thanks to a technique known as wear levelling, few residential users are ever likely to force their drives to fail through overuse.

As we’ve said, each individual cell (which is used to record either a 0 or 1) can only have data written to it a certain number of times before it fails. The key to prolonging the life of an SSD therefore lies in ensuring that data is written to each cell in the most efficient manner possible – which is why wear levelling is so important.

Rather than writing data concurrently (as a HDD would), an SSDs firmware ensures that data is equally distributed across cells. To put it another way, if a user were to save a file to an SSD, the device would first check for cells that had not been used previously and write the data to them before re-using any others. If no such cells were available, it would instead use those that had only had data written to them once, twice etc. in order to prolong the drive’s lifespan.

Two types of wear levelling are commonly used in flash-based media, specifically either static or dynamic wear levelling. Generally, dynamic wear levelling is more likely to be used in consumer-grade drives as it is less complex and offers faster read/write speeds, but also results in a drive having a shorter lifespan. Static wear levelling is more complex and slower but offers a longer lifespan and is favoured by commercial users as a result.

So, if not for wear levelling, a lot more people would find themselves needing SSD data recovery services!

Luckily, whatever technique your SSD or flash media uses, you can rest assured that we’ll be able to recover your data if it ever fails.