[Samba] Restore Samba from backup

[Viktor Trojanovic]

While I'm still trying to figure out how to repair my Samba AD DC, I need
to work on a plan B. Plan B means restoring the DC from backup and,
according to the Wiki entry about restoring pre 4.9. backups, the list
should be consulted if there are no other DCs alive. As is here the case
since this was a single DC setup.

Back in the days, the backup wasn't set up by me and it seems that it
doesn't follow best practice per the Samba wiki. Specifically, backup is
not done using the official Samba backup script but just doing a tar with
option xattrs on the whole Samba folder.

In this specific case, we are not speaking about a full disaster though.
Everything is still pretty much in place, I have especially no indication
that there is something wrong with the sysvol folder.

Kindly confirm if these are the steps that need to be taken in order to do
the restore:

1. Downgrade Samba to the the last working version (4.7.4. in my case).
2. Stop Samba
3. Backup and remove smb.conf and remove all *.tdb and *.ldb files from the
Samba folder, as well as /etc/krb5.conf. Also backup and remove sysvol.
4. Provision new AD on same machine with same IP and hostname and test it.
5. Stop Samba, restore smb.conf, restore *.tdb and *.ldb files, restore
sysvol

Thanks,
Viktor