US Patent 11875864 Mitigating edge layer effect in partially written blocks

A storage device includes 3D NAND including layers of multi-level cells. When a shutdown command is received, whether a block is partially written is evaluated. If so, dummy lines are written after the last written wordline of the block. Partially written blocks may be those having a fill percentage less than a threshold. The threshold may be a function of the PEC count of the block. If a maximum retention time is exceeded by data stored in a partially written block, dummy lines may also be written to the block.