1. In a primary system that has a primary mass storage and is in communication with a secondary system that has a secondary mass storage, a method for mirroring and archiving the primary mass storage on the secondary mass storage, the method comprising: after the secondary mass storage has been synchronized with the primary mass storage, tracking changes to the primary mass storage during a time interval; identifying an end of the time interval by identifying when the primary mass storage is in a logically consistent state; using the tracked changes to create an update that includes any tracked changes necessary to represent the state of the primary mass storage at the end of the time interval; and transferring the update to the secondary mass storage, such that the secondary mass storage can be brought current with the logically consistent state of the primary mass storage.