[Samba] both Samba-4.9.5 AD DC upgrade to Samba current (4.22.*) - questions

[Peter Milesson]

On 29.06.2025 19:11, Franta Hanzlík via samba wrote:
> We are preparing to upgrade our two Samba AD DCs during this school
> holidays. Both current DCs are x86_64 VMs with Samba 4.9.5, AD schema
> = 47 (Server 2008R2), there is one AD domain.
> We expect to upgrade to Samba 4.20.* or 4.22.* and AD schema to current
> Server 2019 or 2022.
>
> Can you please advise on the optimal upgrade procedure, and possibly
> give some general recommendations and warnings about possible issues?
>
> According to the Samba Wiki at
>    https://wiki.samba.org/index.php/Upgrading_a_Samba_AD_DC
> , it seems that this procedure might work:
>
> - on FSMO DC, backup domain (samba-tool domain backup online ...)
>
> - demote non-FSMO DC (samba-tool domain demote ...), shutdown VM
>
> - run new VM with actual Samba-4.22.x DC installed, with same hostname,
>    realm,... as had previously removed machine.
>
> - join to domain (samba-tool domain join ...)
>
> - start Samba and run AD replication status and Samba AD DC database
>   check (samba-tool drs showrepl ... / samba-tool dbcheck ...)
>
> - transfer FSMO role to newly joined DC (samba-tool fsmo transfer...)
>   (is it really needed? What about seizing a FSMO Role at the whole end?
>   - but Wiki say FSMO transfer is recommeded before seizing)
>
> - demote former FSMO, stop Samba and shutdown this old VM
>
> - run another new VM with actual Samba-4.22.x DC prepared, with same
>    hostname, realm,... as had previously removed former FSMO.
>
> - join it to AD, start Samba, check replication and DB status, maybe
>    transfer FSMO here again..(or seize FSMO here?)
>   
> - upgrade AD schema version (samba-tool domain schemaupgrade...) to
>    value 88
>
>
> Apart from the fact that I am not sure that the above procedure is correct
> and optimal, there are still some ambiguities, e.g.:
>
> - already mentioned above - can there be no server FSMO role defined
> anywhere (during the upgrade)? (and then seizing if at final end)
>
> - Since Samba-4.9.5 supports a higher (but experimental) schema 69
> (Server 2012R2), wouldn't it be better to upgrade the AD schema to this
> level on the old DCs (and at end only do a schema upgrade 69 -> 88)?
Hi Franta,

I have upgraded a few times, and I have found that the simplest way is 
creating one or more AD DCs on VMs from the most recent Debian 
backports, and join them to the existing domain. When everything seems 
to work, transfer the FSMO roles, and demote the old DCs. After that, 
you can raise the forest and domain levels. And if you don't use 
rfc2307, make sure to disable this when promoting the new DCs. Trying to 
upgrade the old DCs is asking for lots of trouble. Installing new VMs is 
really a snap, cheap and efficient.

Just as a side note, I set up a new Windows 2025 DC in a VM a few days 
ago, and that was an experience I wish nobody will experience. 
Incredibly buggy. At one point, I was almost on the way to throw it out, 
and replace it with a Windows 2022 DC. Never had those problems with Samba.

HTH.

Best regards,

Peter