While they give a measure of persistence to the data (in that the database does not lose everything in the case of a system crash) they only offer partial durability (as 'recent" changes will be lost). For full durability, they need supplementing with one of the following: Transaction logging, which records changes to the database in a journal file and facilitates automatic recovery of an in-memory database. Non-Volatile DIMM (NVDIMM), a memory module that has a DRAM interface, often combined with NAND flash for the Non-Volatile data security.