In the backup schedule, use the Number of Backups to Keep option to specify how many backups of the selected databases to keep. The maximum is 99; however, your machine may run out of disk space before reaching that amount.
For example, create a backup schedule that runs once a day at 6:00 PM and keep a maximum of seven backups, which is a daily backup for one week. On the eighth day that the backup schedule runs, FileMaker Server automatically deletes the oldest backup—the one created on the first day—and replaces it with a new backup.
Each time a backup schedule runs, FileMaker Server creates a new subfolder within the backup folder you specified. The name of the new subfolder is a combination of the schedule name and the local server date and time when the backup schedule runs (for example, DailyBackup_2018-07-25_1800). When the total number of backups reaches the maximum number you specify, FileMaker Server deletes the oldest backup subfolder in the backup folder.
•If there is insufficient disk space on the destination disk for a new backup, FileMaker Server deletes one or more of the oldest backup subfolders to create the free disk space required for the newest backup.
•If you change the name of a backup schedule, FileMaker Server renames all existing backup subfolders to match the new name.
•If you change the backup folder of a backup schedule, FileMaker Server cannot automatically move the existing backup subfolders. You must manually move them to the new backup folder to have FileMaker Server count them toward the maximum backups to keep.
•If you decrease the value for Number of Backups to Keep, FileMaker Server deletes the extra backup subfolders, starting with the oldest.
•If you set Number of Backups to Keep to 0, FileMaker Server places the backup file directly in the specified destination folder without creating a timestamped subfolder.
•If you remove a database from a backup schedule or if the database is no longer hosted, FileMaker Server eventually deletes that database from all backup subfolders as it reaches the maximum number of backups.