To me these hard disks are one step removed from optical backups, which I used to make. The more "offline" the better. Even the currently local set is kept un

To me these hard disks are one step removed from optical backups, which I used to make. The more "offline" the better. Even the currently local set is kept unplugged between updates. Also keeping a NAS at another location means having internet access at that location. The work network/firewall would not permit this use, for one thing.