An example memory system may include a central processing unit (CPU) comprising a CPU cache, a storage class memory, a volatile memory and a memory controller. The memory controller is to store, in the storage class memory, a first cache line including first data and a first directory tag corresponding to the first data. The memory controller is to further store, in the storage class memory, a second cache line including second data and a second directory tag corresponding to the second data. The memory controller is to store, in the volatile memory, a third cache line that comprises the first directory tag and the second directory tag, the third cache line excluding the first data and the second data.