Moving sectors within a block of information in a flash memory mass storage architecture

In a memory controller for use with a host requiring access to a nonvolatile memory, the controller being responsive to a logical block addresses (LBAs) received from the host, a group of LBAs for identifying one or more information blocks to be accessed in the nonvolatile memory, each of the information blocks including a plurality of N sectors, the nonvolatile memory including a plurality of selectively erasable block locations, each of the block locations having a plurality of physical block address locations (PBA locations), each of the PBA locations for storing a portion of an information block, the controller being operative to develop physical block addresses (PBA's) for addressing corresponding ones of the PBA locations, a method for storing and retrieving portions of an information block to and from more than one of the block locations, the method comprising the steps of:

• receiving a first write command indicating a particular LBA, and receiving an information block indicated by the particular LBA from the host, the information block including a plurality of original sectors, the first write command requesting the controller to store the information block in the nonvolatile memory;
• determining a first block location which is free;
• storing the information block in the first block location;
• receiving a second write command indicating the particular LBA, and receiving at least one rewrite sector superseding corresponding superseded ones of the original sectors of the stored information block, the second write command requesting the controller to rewrite the at least one rewrite sector to the nonvolatile memory;
• determining a second block location which is free;
• storing the at least one rewrite sector in the second block location;
• generating and storing mapping information associated with the particular LBA, the mapping information including,
• a first virtual block address indicating the first block location,
• a second virtual block address indicating the second block location, and
• status information indicating whether any of the original sectors of the stored information block have been superseded;
• whereby the controller avoids transfer of the entire particular information block to another block location each time the host requests that a portion of the particular information block be re-written.