Backup of a node is not really possible.
Node is getting new data all the time, if you restore a backup that is a few hours old, it will not have the data of the last few hours, will fail audits and be disqualified. There is no way to tell the satellite that “hey, this node has just been restored from a backup, so it does not have any pieces uploaded to it since date xyz”.
The only way to achieve reliability is to use RAID or something like Ceph that replicates the data in real time.