Memory system and a method for garbage collection of the memory system

A memory system having a controller and a memory, the controller includes a processor and a copy buffer, and the memory includes a to-be-collected virtual block (VB), a cache and a target VB, wherein the processor is configured to:

• read N valid data sets in the to-be-collected VB out to the copy buffer sequentially, where N is an integer greater than or equal to 2;
• transfer a valid data set in the copy buffer to a corresponding cache, and read a next valid data set out to the copy buffer;
• and
• program the valid data set in the cache to a corresponding target die group of the target VB, wherein a time period in which a current valid data set is programmed from the cache to the target die group corresponding to the cache overlaps at least partially with a time period in which a next valid data set is read from the to-be-collected VB to the copy buffer.