One of the most important simulation assets is the data that is collected during executions. Imagine being able to look back, analyze and reuse the data of simulations that have been run during the last decade. However, data logging has a number of challenges, not the least in today’s environment where we need to train jointly and combined and mix a number of Live, Virtual and Constructive simulators, using dierent standards. This paper summarizes some requirements for Live, Virtual Constructive (LVC) data logging as well as replay. It also describes some early experiences from developing and testing a data logger that can perform fully synchronized, simultaneous data logging of High Level Architecture (HLA), Distributive Interactive Simulation (DIS), Link 16 and other data streams. Some details are given on aspects like embedding, chase play, ownership and import/export. Some challenges and limitations when mixing these dierent interoperability and data link standards are also covered.