A computer-implemented method, according to one embodiment, is for maintaining heat information of data while in a cache. The computer-implemented method includes: transferring data from non-volatile memory to the cache, such that the data is stored in a first page in the cache. Previous read and/or write heat information associated with the data is maintained by preserving one or more bits in a hash table which correspond to the data in the first page. Moreover, the data is destaged from the first page in the cache to the non-volatile memory, and the one or more bits in the hash table which correspond to the data are updated to reflect current read and/or write heat information associated with the data.