Since then I've been doing some research, and I haven't found an answer to the main question I've been asking, so here's the question:
How can I perpetually make copies of only the last 7 days of backups immutable?
I don't want to use my S3 Object storage to "extend" my SOBR; I don't have enough money for that! I only want to use it to keep copies of the last 7 days of backups (ideally a full and 6 forever-forward incrementals), and make those immutable.
(I already have backups, backup copies offsite, GFS jobs from those backup copies, VM replication jobs going to a hot-standby vsphere cluster, and quarterly tape archives of all backups.)
If this is possible, what settings do I use? Are are they in the backup job, the backup copy job, in the SOBR settings, or...somewhere else?
Thanks!