When a master backup is performed on the Unitrends agent, the system is scanned for an existing change journal on each volume. If a change journal does not exist on a volume, the agent creates one. If a journal does exist, the agent insures that the size of the journal meets the minimum size required by enlarging the journal if necessary. The minimum size required for a change journal is 500MB. After the journal creation/discovery is complete, the agent “registers” each journal by creating entries in the system’s registry. Subsequent incremental backups query these entries. The registry entries exist outside of the current Unitrends registry entries to insure that they are not removed following agent software updates or software removal. The agent records a registry entry for each volume containing a change journal. The registry entry contains the following:
• a unique ID given to the change journal
• the sequential number of the first entry in the journal