Everything that can store analog data can store digital data, but not the other way around. So magnetic tape is analog because it can store analog data. A hard drive disk is digital as it can only store digital data.
Something that stores analog data can store digital data by assigning the highest values to 1 and the lowest to 0. So in the end calling something digital by it's capacity to store digital data is misleading as all analog devices in theory can be digital.