Controller and Method for Using a Transaction Flag for Page Protection

A controller comprising:

• one or more interfaces through which to communicate with a plurality of memory dies, wherein at least some of the plurality of memory dies contain multi-level memory cells operative to be programmed with at least two bits of data;
• an interface through which to communicate with a host;
• and
• a processor in communication with the one or more interfaces, wherein the processor is configured to:
• receive a command from the host to program data in a plurality of lower pages and a plurality of upper pages of the multi-level memory cells;
• detect an indication from the host that indicates which previously-programmed lower pages from a previous program command are at risk of being corrupted by the programming of the upper pages from the received program command;
• and
• prior to programming the upper pages, back up the previously-programmed lower pages from the previous program command that are at risk of being corrupted but not the lower pages of data programmed by the received program command.