jameswilson
Did you read the Affa wiki ?
Affa uses hard links so compression is probably not viable.
You would need to reduce the number of old backups retained using the settings for
scheduledKeep
dailyKeep
weeklyKeep
monthlyKeep
yearlyKeep
and then use the command
affa --cleanup JOB
to remove the old backups, to quote
"After you have lowered a keep value, e.g. , then archives with a higher indices will no longer be shifted and will exist for ever. This option finds these archives and deletes them. you can delete or purge the oldest backups"