Once I get the scans done, they are transferred to RAID5, and once I have enough drives, onto an external RAID5 that is stored offsite.
This gets time consuming and expensive.
In all honesty, if I could afford it, I’d do a film-out back to 35mm, it is likely to outlast digital copies, especially with the new breed of archival film. In a hundred years, you can still utilise a well stored 35mm print, whereas it is getting difficult to access digital data from just 20 years ago.
Digital archives require constant maintenance and checking for corruption, and transferring to new media every few years, a good film archive just has to be kept cool and relatively dry.

At the moment LTO is a reasonable option.