Lohkokaista

Lohkokaista, often anglicized as "block erase," is a term used in computing, particularly in the context of flash memory. It refers to a fundamental operation for deleting data from a flash memory device, such as a solid-state drive (SSD) or USB flash drive. Unlike byte-level or page-level erasure, block erase operates on larger, contiguous segments of memory known as blocks.

Flash memory stores data in pages, and pages are grouped into blocks. To write new data to a location that has already been written to, the entire block containing that location must first be erased. This is because flash memory technology requires a full block to be erased before it can be rewritten. Attempting to overwrite data directly on a flash memory chip without an erase operation will result in data corruption.

The block erase operation is significantly slower than writing data to a page. This performance characteristic is a key factor in the design and operation of flash memory controllers, which employ wear-leveling algorithms to distribute writes and erasures evenly across all blocks to prolong the lifespan of the memory. When a user deletes a file, the operating system or file system doesn't immediately erase the data at the byte level. Instead, it marks the pages or blocks containing that data as free, making them available for future writes. The actual block erase operation happens later, typically in the background by the flash memory controller during idle periods or when the block is scheduled for rewriting. This process is essential for managing the complexities of flash memory storage and maintaining its performance and longevity.