I'm relatively small-fry when it comes to backups, but ZFS got mentioned here a few times
D800 shooting to SD/CF (backup arrangement). Ingestion into primary machine (a Mac laptop) and displayed to check for problems. Images then transferred after processing to a computer running Debian with ZFS; each ZFS pool is replicated onto at least two disks. CF cards read via camera if/when an error is detected with the SD card (so far unnecessary -- unless I've been experiencing silent corruption). After comparing SD card contents and copy on ZFS, the SD cards and CF cards are formatted. The Debian machine is only used for storage and is usually offline. Scrub once a month. Only one of the seven drives that it's had has reported errors so far (and then the drive died).
ZFS snapshots used to reduce the likelihood of human error wiping out everything.
Haven't figured out how to economically and quickly run off-site backups; currently using sneaker-net for large files and git for smaller data.
Fortunately, the one time I experienced the need for off-site backup (a fire), a then-mid-sized hard drive could comfortably store everything that needed backing up (and more). Nowadays, D800 NEFs are far too unwieldy (as are the corresponding multi-gigabyte layered edits) for the lowly likes of me.