Retention policies define the length of time you retain historic data based on daily, weekly, monthly, or yearly time intervals. You can create Barracuda Backup retention policies for different sets of data including virtual machines (VMs), agent data (Exchange, SQL, Hyper-V, System State), network file share backups, and Microsoft Exchange email messages.
Data backed up using Barracuda Backup treats Sunday as the end of week in accordance with the ISO date standard. All revisions are used when a backup schedule is repeated multiple times in a given day. The last backup in a day, or in some cases the only backup of the day, becomes the Daily revision. The last backup of the week becomes the Weekly revision, while the last backup of a month or year becomes the Monthly or Yearly revision.
Figure 1 illustrates how revisions are created in a given month if a backup is run every day.
Figure 1. Revisions in a Given Month.