You could always prepopulate the drive(s), then do incremental backups.
Yeah that's exactly what I'd do. Fill with initial data and then nightly afterwards.
I've currently got
Main Home Server - with an amount of storage, maybe around 10TB
Storage server - currently with 2 x 14TB drives in a ZFS mirrored array.
Plan is to migrate the lot to the Storage server which will backup to itself. Somehow.
Then I wanted a copy off site.
I suppose the upload speed at parents isn't an issue for recovery, since if I wanted the full backup I'd literally go and get it.
Aye, I suppose that's the main advantage of an off-site backup at a location that you can physically access still.
I have a "backup to itself" system in place on my main PC at present incidentally. Backup hard drives (which are not mounted by default), script runs once a week to mount the drive, do an incremental backup then unmount it again. Process has worked well so far - combined with an external backup as well of course.
My PLEX disks are backed up every night to a duplicate set in the same box. My laptop and Mrs WmA's laptop do file history backups throughout the day to a Raspberry Pi and these disks are backed up with an Rsync to a duplicate set. Other bits of kit around the place are backed up/duplicated as well (plus I keep all my important docs and things on an Owncloud server). I suppose I really should look at something "off-site" even if it's some ethernet string and an extension running out to the shed.
It's honestly got me thinking, I have an old NAS (liberated from work) with 4.5TB capacity. Currently it sits on my desk and I do periodic backups to it. I'm considering running a network cable to the far loft corner of my garage and sitting it there. OK it's not really offsite, but would stand a much, much bigger chance of surviving either a fire or a burglary.
Well I'm saying goodbye to Virgin cable in a week, so what with all the cable-shuffling maybe I'll actually get round to doing something.