fonctionnement initialisation du sysvol
https://blog.piservices.fr/post/2017/04/05/active-directory-de-l-importance-de-l-initialisation-du-sysvol-dans-un-dcpromo

replication non autoritative
http://kpytko.pl/active-directory-domain-services/non-authoritative-sysvol-restore-dfs-r/

autoritaire
http://www.nomizo.fr/2013/08/windows-server-2012-issues-with-active_16.html

http://kpytko.pl/active-directory-domain-services/authoritative-sysvol-restore-dfs-r/

http://windowsitpro.com/windows-server-2012/fixing-broken-sysvol-replication

Which points to this MS KB:
https://support.microsoft.com/en-us/kb/2218556

http://jackstromberg.com/2014/07/sysvol-and-group-policy-out-of-sync-on-server-2012-r2-dcs-using-dfsr/

Problème de démarrage après l’installation de la mise à jour KB2919355 sous Windows Server 2012 R2