Thanks Jay
I have been able to restore a backup linode to another linode (linode2)
Now I need to open Discourse on linode2 so that I can get Discourse to email me a backup.
I made a new DNS setting for linode2 but I get 502 Bad Gateway when I go there.
Perhaps I have to wait a while?
Strangely discbak.softwarebydesign.com.au (linode2) is currently re-routing to discourse.softwarebydesign.com.au (on the original linode)