configuring, in the SSD, a low-level cell for storing open block data to form a low-level cell block;

in response to receiving a data write instruction, writing data into a high-level cell of the SSD, wherein the high-level cell has a unit capacity higher than a unit capacity of the low-level cell;

in response to that an existing time of a block which is not full of data in the high-level cell exceeds an open block status threshold value, determining the block that is not full of data as an open block and storing the open block in a pending list; and

in response to the existence of the open block in the pending list, transferring the open block to the low-level cell block through an internal memory, and closing the open block in the low-level cell block, increasing the open block status threshold value after transferring the open block to the low-level cell block through the internal memory;

wherein the low-level cell is a Single-Level Cell (SLC) or a Multi-Level Cell (MLC); the high-level cell is a Trinary-Level Cell (TLC) or a Quad-Level Cell (QLC); and a data writing speed of the low-level cell is higher than a data writing speed of the high-level cell.