This is a rare condition, that would happen on this scenario:
- There are N Files on the journal.
- The last file is empty, not being used at all (no records added)
- Compact is started
- More records added while compacting is running
- The server is stopped.
The file that was empty will be used in a wrong order, now new records will be out of order (updates and deletes being placed before the insert).
if you now kill or restart the server before the file is reclaimed, you will get in a situation where the server can't be started.