System for the storage and maintenance of data sets updates in a storage subsystem, that comprises direct access storage device(s) that serves as the main storage of the storage subsystem and on which the data sets are originally stored; a Cache memory storage device that enables fast interaction with the storage subsystem, on which a copy of the data sets is stored; a non-volatile storage device partitioned into a plurality of fixed size non-volatile memory pages. The system employs an update process, in which the changes to the data sets are applied to the data set copy stored on the Cache memory device; a journal of the changes that are being made to the data sets stored on the Cache memory device, utilizing the non-volatile memory pages to store update records reflecting the changes in the data sets; a reconstruction process in which the data sets are reconstructed utilizing the update records stored on the non-volatile memory pages, and the data sets stored on the direct access storage device; and a process for freeing arbitrary non-volatile pages from their prior association with data sets that are stored in the Cache memory.