Solid state storage garbage collection (GC) is the process by which a solid state drive (SSD) improves write performance. Garbage collection, like TRIM, pro-actively eliminates the need for whole block erasures prior to every write operation.
When a file is deleted from a computer, most operating systems (OSs) delete the table of contents entry, but do not delete the actual data blocks from the storage media. Hard disk drives will simply overwrite the unneeded data blocks. Flash SSDs, however must erase the unneeded data blocks before new data can be written. Working in the background, garbage collection systematically identifies which memory cells contain unneeded data and clears the blocks of unneeded data during off-peak times to maintain optimal write speeds during normal operations.