wear levelling
also: WL, dynamic wear leveling, static wear leveling
Wear leveling is a technique that distributes write operations evenly across all memory cells in solid-state storage (SSD/flash) to prevent premature failure from overuse of specific locations.
Modern SSDs use flash memory, where each cell can only endure a limited number of write cycles (typically 10,000 to 100,000+) before degrading. Without protection, the operating system might repeatedly write to the same physical locations, causing those cells to fail while others remain unused.
Wear leveling is handled transparently by the SSD's firmware controller. It remaps logical block addresses (what the OS thinks it's writing to) to different physical memory locations across the drive. This ensures all cells age at approximately the same rate, extending the drive's overall lifespan.
Example: If your OS writes a frequently-updated file 1000 times, wear leveling redistributes those writes across different physical flash cells each time, rather than repeatedly using the same cells. A drive might survive 5 years of heavy use instead of 1 year without this protection.