I do not have full proper offsites... yet.
I run proxmox, so if it's live on a server it's probably on my ~70TB (really 40*2TB ssd) ceph cluster. Which makes 3 copies across the 5 boxes, so it's more like 23TB of usable space for all my vms and such.
The 400TB of storage is Truenas is really closer to 300TB after all the losses in raidz vdev and hot spares and what have you, there's 30x 16TB SAS seagates in the box, of which 2 are hot spares and 7 are parity for raidz1... For things that are slow or linear loads (a movie file could be a good example of that type of workload!). Backups of the the proxmox boxes... and mass stored stuff, 99% of it I could easily obtain again if I had to. Although I'd probably be pretty flustered about it.
Truly important stuff gets written to 100GB bluray(s) (specifically m-disc blurays) and put in the safe. I do this probably about once a year or so...
My dad was in the process of setting up his own cluster that's running 14TB drives rather than my 16TB... When he's finally done I intend to requisition probably about half of his space for offsite storage (maybe more). I'm figuring about 100TB of space is what I'll have there. Maybe more. He's about 65 miles away from me, different electrical grid and all.
So the count as it stands now. Everything running has at least 2 copies on 2 mediums (ceph cluster, and spinning rust). My "linux iso" repositories only live on the spinning rust storage, but is low priority anyway. Super important highly sensitive shit lives on at least 3 copies and 3 mediums, although one of the mediums may be out of date and none is offsite... Though it's rare I add to this category. There is plans for adding another copy of data, offsite on harddrive storage for most of my dataset as it is now.
Truenas usages:
And here's Ceph