Regarding the “local” replication:
There is no such built-in way in Rockstor, but you can try one of the following:
- Have a 2nd rockstor applience to which your USB drive is attached and use the Rockstor replication
(e.g. even a RaspberryPi 3+ / 4 will do the job, or you could also think about running the 2nd applience as a virtual machine) - There are also Rock-ons for backup purpose including deduplication & compression (have a look at Duplicati 2.0)
- Use any other generic linux backup tool by installing and configuring it in the OS of your Rockstor machine. My favorite tools are:
- BorgBackup (deduplication & compression), or the great “wrapper” Borgmatic if you prefer to work with config files
- btrbk utilises btrfs send & receive to “clone” btrfs subvolumes to an external drive including deduplication (but no compression)
I use btrbk to “clone” my relevant BTRFS subvolumes to an external (USB 3.5" HDD-Bay) for offline & remote backups (at my parents home) and can recommend this approach if you are willing to set btrbk up by yourself.
Alternatively, the probably easier approach is to simply set up a 2nd applience with a Raspbery Pi and use the Rockstor replication feature.
Cheer Simon