I regularly (each 4-6 months) do a backup of pictures from mine and wife's phones.
In the same process I also backup from my main computer documents or pdfs, bookmarks, certain video files from my Plex collection, etc. All sorted into the folders with date ranges on them to easily find later. First on a physical external HDD and then manually upload the same folders to Onedrive following the same folder structure.
I am looking for a cloud backup that will automatically sync everything on an external HDD on demand. So when I have all my files and folders moved over to HDD, it will match what's already uploaded and only sync the new stuff.
An important condition is that the external drive will only be plugged in during the backups, I know some services require it to be mounted or they delete the cloud data after some time.
Any suggestions on what's best to use? I'm working with 1-2 TBs of data total.
Thanks!