1. A host system comprising: a memory device; a flash memory comprising a plurality of N physical blocks; a processor configured to allocate a selected region in the memory device as a task space and generate a control command when a task request directed to a data file is received; and a flash controller configured to program a flash memory file system, wherein the flash memory file system; (a) maps N logical blocks to the N physical blocks, (b) divides the N logical blocks into M logical groups, where the M is less than N, (c) loads erasure data for only one of the M logical groups into the selected region of the memory device in response to the control command, and (d) scans only the erasure data loaded into the memory device in response to the control command.