DATA RANDOMIZATION FOR FLASH MEMORY

摘要

Data words written to an SSD device, or other device or output data stream, may be randomized using a seed based on physical addressing information, such as a page address, column address, and a cycle count for the page address. This enables the storage and de-randomization of variable length data blocks stored at random locations within a page without requiring storage of additional data, which would make recovery impossible if lost in prior approaches. The page address, column address, and block address are physical attributes of the storage location for the data word and do not need to be saved and therefore will not be lost making recovery of the seed always possible. The cycle count can be saved and, if lost, limited trials with range of cycle counts can be exercised to de-randomize the data word and decoding may be used to determine whether descrambling was successful.

主权项

1. A method for accessing a nand flash device defining a plurality of pages each having a plurality of column addresses, the method comprising:
receiving a write request referencing a page identifier and including a plurality of data words to be written to a page corresponding to the page identifier, each data word of the plurality of data words corresponding to a column address within the page; and for each data word—
randomizing the each data word according to a pseudo-randomization algorithm seeded by the column address corresponding to the each data word and the page identifier to obtain a randomized word; andwriting the randomized word to the page at the column address corresponding to the each data word.