The first time you perform a backup, the DS-Client retrieves the selected files from the backup source and sends the files to the DS-System. Information pertaining to those files is saved in both the DS-Client database and the DS-System online storage.
Each backup set has a backup log table in the DS-Client database. For various reasons, the backup log can fall out of synchronization with the DS-System online storage. If this occurs, a Normal synchronization process is automatically run during the next Weekly Admin process or scheduled backup.
By default, Weekly Admin performs a synchronization only on backup sets marked Out of Sync. To have it perform synchronization on all backup sets, you must configure the AdminSkipSync advanced configuration parameter. 
To synchronize a backup set:
1.Click the Backup Sets tab.
2.Select the backup set you want to synchronize.
3.On the Sets menu, click Backup Sets, and then Synchronize.
4.Under Synchronization method, select one of the following options:
Normal – Compares the DS-Client database backup log with the DS-System's online storage and updates where required.
Check only – Performs a check of the synchronization between the DS-Client database backup log and the DS-System online storage and identifies if inconsistencies exist. No corrective action is taken.
DS-System based – Synchronizes the DS-Client database backup log with the DS-System online storage.
NOTE:  If you perform DS-System based synchronization, you cannot use the “deleted from source…” option if you recover orphaned backup sets because the information related to files that have been deleted from the source is no longer available on the DS-System. To retrieve this information, you must recover the dsclient and dsdelta databases by running a daily or weekly admin on the production DS-Client, and then recover the dsclient and dsdelta databases to another DS-Client. Only then will the restore wizard show exactly the same information in both DS-Clients when performing a restore.
5.Click Synchronize.