[Samba] samba-backup.sh problems - is the /var/lib/samba/etc folder essential in a Samba installation?

[Stephen]

Hi everyone, I am running Samba 4.5.16-Debian on Raspbian OS and I am 
currently attempting to deploy the provided samba-backup.sh script 
within my existing SAMBA installation to implement disaster recovery on 
my AD DC servers.

Following the documentation provided here 
https://wiki.samba.org/index.php/Using_the_samba_backup_script I have so 
far managed a partial success on my backup:

pi at ad1:~ $ sudo /usr/sbin/samba_backup.sh
tar: ./private: file changed as we read it
tar: Cowardly refusing to create an empty archive
Try 'tar --help' or 'tar --usage' for more information.
Error while archiving /usr/local/backups/etc.2019-04-16.tar.bz2 - status = 2

The script aborts with status 2 which is apparently an unrecoverable 
fatal error. If I now do a quick ls we can examine what the script did 
manage to backup prior to it failing:

pi at ad1:~ $ sudo ls /usr/local/backups
samba4_private.2019-04-16.tar.bz2

So we can see that at least ONE of the THREE expected archives has been 
created which is a good start. When I examine samba_backup.sh I notice 
the following line in the script DIRS="private etc sysvol" which appears 
to just be a list of all the directories within /var/lib/samba to 
include within the backup. However when I do a quick ls, I notice am 
completely lacking the specified etc directory within my Samba 
installation - this is why the backup appears to be failing. The folder 
/var/lib/samba/etc doesn't exist on my machine:

pi at ad1:~ $ sudo ls /var/lib/samba
account_policy.tdb  group_mapping.tdb  ntp_signd  printers private  
registry.tdb  share_info.tdb  sysvol  usershares winbindd_cache.tdb  
winbindd_privileged


So my questions are:

1) Should /var/lib/samba/etc folder exist in my installation? Should I 
worry that my installation botched since I appear to be missing it.

2) Related to 1, does /var/lib/samba/etc actually exist, perhaps the 
Debian/Raspbian packagers have moved it somewhere else? Alternatively it 
may be that the etc folder is actually optional and  created on demand 
as needed?

3) Related to points 1 and 2 - Is it absolutely essential to include the 
contents of /var/lib/samba/etc in order to have a viable AD DC backup 
set (as per the current Samba docs)? If not I am just tempted to solve 
the problem by editing the aforementioned DIRS statement in order to to 
skip the backup on the etc folder since it doesn't exist on my machine.

Kind Regards
Stephen Ellwood