Method and apparatus for performing write operations in multi-level cell storage device

Abstract

A memory contains a plurality of memory cells that are capable of storing one or more bits of data in each memory cell. The memory stores, in response to a write operation, data corresponding to the write operation in a first set of the memory cells such that each cell of the first set of the memory cells stores a single bit. Thereafter, data from the first set of memory cells are transferred to a second set of the memory cells such that each cell of the second set of the memory cells stores more than a single bit of data. The write operation to the first set of cells is executed in a foreground operation, and in a subsequent background operation, data from the first set of memory cells are transferred to the second set of memory cells. The memory cells are non-volatile flash electrically erasable programmable read only memory (EEPROM) cells, and therefore require erasure before programming. Typically, memory cells are reclaimed in a background operation. However, if not enough memory cells are available for a write operation, then a set of memory cells are reclaimed in a foreground operation, and more than one bit of the data are stored in the reclaimed memory cells.

Dependencies are inferred from the claim text.