Weekly, monthly and yearly backups are also called archive backups. In the GFS retention policy, weekly backups are known as ‘sons’, monthly backups are known as ‘fathers’ and yearly backups are known as ‘grandfathers’.

GFS is a tiered retention policy and it uses a number of cycles to retain backups for different periods of time:

GFS backups are always full backup files that contain data of the whole machine image as of a specific date. When you configure the GFS retention, Veeam Backup & Replication creates weekly/monthly/yearly full backups, so instead of one backup chain consisting of one full backup and incremental backups, you will have several backup chains. Also, one corrupted increment can make the whole chain useless. Large number of subsequent incremental backups can increase recovery time, because Veeam Backup & Replication has to read data through the whole backup chain. The GFS retention also helps you to mitigate risks that the short-term retention policy has, such as large number of subsequent incremental backups. Depending on which flag is assigned to the full backup, it will be stored for specified number of weeks, months or years. These GFS flags can be of three types: weekly, monthly or yearly. This tool is from Veeam so check it out: I also will update the Tools & Links Section with the Link. For this purpose, Veeam Backup & Replication creates synthetic or active full backup files and marks them with GFS flags. Useful, online tool to help calculate the space needed for the backup chain desired in an environment. The long-term or Grandfather-Father-Son (GFS) retention policy allows you to store VM backups for long periods of time - for weeks, months and years.

Veeam backup space calculator