Successful Backup.
Exchange ESE reports "No log files can be truncated."
Exchange database logs of a Storage Group are shared for all databases of that Storage Group. In order for Exchange to commit / flush / truncate the logs, all of the Databases of the Storage Group must be backed up together.
A. The Application log of the Exchange server will show ESE events for the successful backup and then an ESE event for "No log files can be truncated."
B. The Application Log of the Exchange server shows an ESE event that the Purge failed as the database is offline.