NAS-OS BACKUP

[aka]

I have a NAS setup the wat that my system is residing on a smaller separate drive. How can I backup my system only to an external device ?
When I tried to use external backup it only shows shared folders, but I see no option to backup the entire OS. I want (in case of a disaster to be able to replace this main drive woth the system with another one, resotre system from external drive and see all other drives/folders on other disks as there was no issue). I have for example one RAID-1 setup on 2 drives and want this to preserve if the main OS drive fails).

How can I do this ?

[orion]

As far as I know, you cannot backup ADM OS. However you can backup system configuration (it should be system settings only).