[Samba] Upgrade 4.1.7 -> 4.4

[henri transfert]

Hello to all,

I currently have a samba server with the following specs :

   - Samba 4.1.7 , compiled install from source code (samba wiki guided)
   - CentOS 6.5 x86_64 (VM)
   - AD DC + print server / CUPS
   - Internal DNS server

I'm considering an upgrade to the last stable release 4.4.2.

Since this server is in production with 400 users , 500 computers (XP, 7
Pro, OSX) , NAS members (Synology) , and 15 printers, I can't take any
risks about this upgrade.

- Is there any point I have to take care about before this upgrade ? I read
some problems about RDP authentication in previous releases , is it solved
in 4.4 ? Performance issues ?

- Is the process : ./configure ;  make ; samba stop ; make install ; samba
start , the way to proceed ?

- Is there any data to backup before ? (I plan to backup the entire VM
anyway)

- From the client point of view, in case of 4.4 dysfunction is it possible
to go back to 4.1.7 seamlessly by restarting the 4.1.7 VM (I'd like to
avoid to rejoin 500 PCs ...) ?

Any advise welcome .

Thanks in advance

Henri