Patent attributes
In an SSD including a host interface, controller, non-volatile memory coupled to the controller, and volatile memory, data is stored in non-volatile memory in clusters having a cluster start address and a cluster end address. A mapping table is maintained in volatile memory, which indicates by a trim signature deallocated clusters in non-volatile memory. The trim table is populated with deallocated ranges and an associated offset within the non-volatile memory. The controller receives from the host interface a sequence of commands including a deallocate command including at least one address range including a start address and an end address, or a start address and a length of the address range. The controller processes the deallocate command by selecting one or both of a write-to-non-volatile-memory action and a record-to-volatile-memory action. In cases of power failure, the mapping table is restored for deallocated ranges at specific offsets recorded in the trim table.
