what kind of formulas determine how long you should retain your SQL Server database backups for? Our admins seem to be using a variety of different retention schedules for backups of different critical databases, some databases there are 1 weeks worth of SQL backups, others there are 6 weeks worth. I am trying to determine how exactly you would determine how long to keep database backups for, and for example have you ever restored data from say a 6 week old backup, which would surely incur huge data loss? Or under what circumstances would you need to keep backups for longer than say 7 days? I guess the same principle applies regardless of database platform hence adding it to other DB topic areas.