If you are running backups every 3 days, then your retention rule will have this effect:
1W:1D – for the first week, keep at most 1 backup per day. Since you only back up every 3 days, you’ll have 2 or 3 backups retained by this rule. 3W:1W – for the most recent 3 weeks, retain only 1 backup per week. The earlier rule overrides this for the first week. For weeks 2 and 3 you will have 1 backup each. 6M:1M – for the most recent 6 months, keep 1 backup per month. Again, the earlier rules still apply so your first month will have more than just 1 backup. The second through sixth months will each have one backup retained. 1Y:6M – for the most recent year, keep one backup every 6 months. Again, the earlier rules cause this to not really have an effect until after 6 months pass. The rest of the year (6 month span) will have only one backup total. 2Y:1Y – for 2 years keep 1 backup a year. Earlier rules will cause more than 1 backup in the first year obviously. The second year will only have 1 backup version retained.
After 2 years all backup versions are deleted. So you’ll never be able to restore more than 2 years ago with this retention setting.
Thank you @drwtsn32, I think I understand how the config relates to what (how many backup “copies”) are kept now.
For my updated config of: 3W:U,5M:1M,2Y:6M
Would the following explanation be correct?
3W:U
For the most recent 3 weeks, retain all backups (up to 7 backups, as backups happen ~every 3 days; 3W = 21D, and 21/3 = 7 backups) 5M:1M
For the most recent 5 months, retain a monthly backup (up to 5 additional backups) 2Y:6M
For the most recent 2 years, retain a backup for every 6 months (up to 4 additional backups)