Build companion domain controller alongside Samson

• samson the https://wiki.ucc.asn.au/ActiveDirectory server has no freshly built DC friends
  • (and no successfully tested backups/restores)
    • e.g. export/import style, enabling consistent file-based backups: https://wiki.samba.org/index.php/Back_up_and_Restoring_a_Samba_AD_DC
    • snapshot backups of the whole machine #75 are currently running weekly; but
      • they have not been empirically tested by us for this sort of "database" application
      • can we truly trust them to be a completely atomic snapshot? or to be "crashed" with fresh boot and recover every time?
      • most reliably combined with taking "quiesced" backups with the services or whole server shut down?
  • this is risky, a single-point-of-failure
    • which in turn depends on the running VM cluster
  • something to do with the current configuration is probably why we still have occasional auth problems, e.g. mussel?
    • can we upgrade or rebuild or document our way out of this?
  • ...so making a quick clone and calling it "done" really isn't enough, continuous integration is called for?
  • vucc testbed in https://wiki.ucc.asn.au/NewActiveDirectory

Action items:

• [BOB], [333], and [NTU] to learn more about (SAMBA) AD and how it works, along with Linux AD integration options
• Using this knowledge, build new DC
• Fix any other lingering AD issues that can be tracked in this Issue, or otherwise raise separate issues for them