1. A method comprising: retrieving a first hash value of a first root node in a first tree structure associated with a first secondary repository, wherein the first secondary repository comprises a first machine-readable storage medium encoded with the first tree structure; retrieving a second hash value of a second root node in a second tree structure associated with a primary repository, wherein the primary repository comprises a second machine-readable storage medium encoded with the second tree structure; comparing the first hash value and the second hash value; determining that the first hash value is not equal to the second hash value; retrieving a third hash value of a first data unit associated with the first root node and a fourth hash value of a second data unit associated with the second root node, wherein the first data unit is stored in the first secondary repository and the second data unit is stored in the primary repository; comparing the third and the fourth hash values; determining that the third hash value is not equal to the fourth hash value; and modifying the first data unit in the first secondary repository to be synchronized with the second data unit of the primary repository.