# Level wearing

What is level wearing?

* SSDs change data location to level the number of writing operations across all cells.
* if the location was always the same for changing dates, those cells would burn out quickly.
  * each cell stands ≈ 100 000 erasing cycles.
* firmware is responsible for doing the level wearing in an automated fashion.
* It also required a garbage collection system to identify freed sectors, that weren’t erased yet.

How does garbage collection work?

* it keeps a list of freed sectors.
* one block is erased only when all sectors are marked as free.
* even without a data connection, the garbage collection keeps running on its own and restarts in case of a power outage.
