(grandfather, father, son) A tape rotation backup strategy of maintaining backups on a daily, weekly, and monthly schedule. Backups are made on a 5-day or 7- day schedule. A full backup is performed at least once a week. On all other days, full, incremental, or differential backups (or no backups at all) are performed. The daily incremental, or differential, backups are known as the son. The father is the last full backup in the week (the weekly backup). The grandfather is the last full backup of the month (the monthly backup).