Example storage systems and methods provide data storage management using change values in a key data store. A key data store includes a set of key data entries that each include a key value associated with a storage operation, a precondition value, and a postcondition value. A storage parameter is calculated using the precondition value and the postcondition value for each key data entry the set of key data entries. The calculated storage parameter may be reported to manage storage configuration and operations in the storage system.