I'm just about to add more storage to my server. I have 6x6TB drives and I originally assumed I would do a RAID 10. But then I got to wondering if it would be better to do 3 raid 1 arrays each as a member of the backup set. Then, if I understand Recycling correctly, when the backup set gets full, the first RAID1 member could be recycled and made the most recent member of the Backup Set. Combining this with Periodic Snapshot Transfers to archival media would make for a manageable method of keeping the size from getting out of hand.
Please fill it full of holes. I feel like I'm still trying to figure out long term backup storage management is supposed to work. I'm not using tape.