How to make use of external drives with TrueNAS SCALE?

Hi there, I have a couple of external hard drives which I would like to use in an easy way as cold backup for my TrueNAS SCALE. Are you aware of any options?

I tried a replication job, under "Data Protection" however when I tried to disconnect, the test server lost the network conenction... (even after deleting the replication job).

Any ideas?