[Samba] Replace SBS2003 with Samba4

[Anastasios Papadopoulos]

Hello all,

I'm currently investigating the option to completely replace a SBS2003 DC
with a Samba4 DC. My research (mostly on samba.org guides) shows that it is
feasible, however I'd like to get feedback from the community on my goals.

Current status:
A Windows SBS 2003 is the PDC and a W2008 R2 server is acting as secondary
DC. Domain operational level is 2003.
There are ~40-50 users/workstations using the SBS as file server.
Until recently, SBS was also the mail server (built-in Exchange 2003) but a
couple of months ago we migrated to Office 365. The migration included the
setup of DirSync so our AD syncs with O365 for users/groups/password etc.
Exchange is still running but w/o any mailbox or clients using it.

My goals (please fill free to correct the order or comment on the
feasibility of each step):

- Setup a new Samba4 DC
- Join the Samba4 to the domain
- Assume all roles from SBS2003 (FSMO)
- Configure DirSync so that it still syncs AD changes to Office 365
- Migrate all files from SBS to Samba4 (either to Samba PDC or a new
Samba4 member server)
- Demote the SBS2003 server (and eventually recycle it...)
- Demote the W2008 R2 server (so it only serves as member server, i.e.
SQL Server). A second Samba4 DC can be installed to achieve redundancy
- (Optional) Continue using current ADUC console for user management etc

I guess the really tricky part would be to maintain DirSync functionality
while replacing the DCs.

I'd like to hear your thoughts: Are those goals doable? What should I watch
for or avoid?

Thank you very much,