Mutable portions of data are stored in a first storage system and immutable portions of the data are stored in a second storage system. Immutable portions and mutable portions of the data associated with the same time period are initially archived. After a period of time since the initial archiving, the mutable portions of the data from the first storage system that have been modified are supplemental archived. Integrity verifications of successfully performing the initial archiving and supplemental archiving are stored.