 marking sector 123 free since it never was properly filled, and removing any record of XYZ from the file directory).It relies on these items being committed to disk in sequential order.Suppose a caching algorithm determines it would be fastest to write these items to disk in the order 4-3-1-2, and starts doing so, but the power gets shut down after 4 get written, before 3, 1 and 2, and so those writes never occur.