1. A storage device comprising: a flash memory to store data and having a plurality of blocks; and a controller to calculate a life value of the flash memory based on counts to a group of blocks of the flash memory, wherein each block of the group of blocks has a writing count equal to or greater than a first threshold value, wherein the first threshold value is determined based on a maximum writing count of the flash memory, wherein the life value is calculated by using (i) a maximum value among the writing counts of the group of blocks, (ii) a variance of the writing counts of the group of blocks, (iii) a maximum value of the variance, and (iv) a weighting value having a real number from “0” to “1”, and wherein backup operations related to the storage device are performed when the life value is equal to a second threshold value or greater.