- yes to epoch system
- each epoch has a version file, an initial snapshot, and an event log database file
- we will need to add code to vere to find the latest epoch folder before loading snapshot and event log
- there are two separable operations involved in truncation:
- create new epoch, by copying snapshot into a new epoch folder, creating a new version file in that folder, and creating a new event log database file in that folder whose events db is empty and whose metadata db contains entries copied from the previous epoch's metadata db
- a "keep only N recent epochs" command, which removes all epoch folders older than that