Deduplication and compression evaluation methods and systems involve one or more processors generating a hash value for each block of data in a block storage device and creating a random substitution cypher using the respective hash values for each of said blocks of data as seed values to a random number generator. Thereafter, positions of run lengths for each of said blocks of data are randomly shuffled by the one or more processors with no run lengths having identical run length values disposed adjacent one another, a synthetic version of each of said blocks of data is generated using the substituted, shuffled, run lengths.