[Samba] DC upgrade questions

[Pietro Stäheli]

Hi folks,

Yet another upgrade question! Reading the mailing list regarding
upgrades in the past few months has made me a little apprehensive.

After now running a single Samba DC for a few months and excising the
last remnants of the old Windows DC, I would like to join another Samba
DC to the existing one.

Current one (DC2) is running Samba 4.5 on Debian Stretch. samba-tool
dbcheck looks clean after removing entries from previous Windows DC.

My plan is to join a Samba 4.10 DC (DC3) on Debian Buster using Louis'
packages, transfer FSMO roles and sysvol to this one, then upgrade DC2
to Buster and Samba 4.10 (with steps to 4.7, 4.8 and 4.9 in between).

Is this the best approach to do this? Is it necessary to demote DC2
first? The demote/rejoin procedure is recommended for 4.7 and up, so I'm
not sure that this is also recommended for 4.5.

Best regards,
Pietro