Enhanced MLC solid state device

摘要

Flash memory drives and related methods are disclosed that operate to keep frequently written data, which results in frequently erased blocks, in SLC-mimicking MLC flash, and relatively static data in normal MLC flash. A flash drive according to the present disclosure keeps track of the number of times that data for each logical block address (LBA) has been written to the flash memory, and determines whether to store newly received data associated with a particular LBA in SLC-mimicking MLC flash or in normal MLC flash depending on the number of writes that have occurred for that particular LBA. Dynamic allocation can occur between the two types of MLC. Related methods and software are also described.

主权项

1. A method of storing data in a flash storage device comprising SLC-mode MLC and normal mode MLC flash memory, the method comprising the steps of:
receiving a write command comprising a logical block address from a host; mapping the logical block address to a physical address of one or more memory channels of non-volatile memory including SLC-mode flash memory MLC and normal mode MLC flash memory; checking an erase count of a data block corresponding with the physical address; moving a logical data block stored at the physical address to a second data block in the SLC-mode flash memory if the physical address is in the MLC flash memory and the erase count satisfies a predetermined threshold; identifying one or more lowermost write count values for one or more data blocks in each of one or more flash memory channels associated with the SLC-mode flash memory; selecting a write threshold value greater than the one or more lowermost write count values but lower than write count values associated with one or more other blocks in the one or more flash memory channels; and moving a data block stored in the SLC-mode flash memory back to the MLC flash memory when the stored data block has a write count satisfying the write threshold value.