SYSVOL is shared automatically on Domain Controllers, not on any other an other roles. You may confirm via net share command. For every type of workstation or server (including Domain Controllers, member servers, workgroup computers) every machine with Windows OS (except Windows home edition) has a local policy that is applied to the machine. If the machine is a domain member then additionally site, domain, OU based policies apply to the same machine in order. If a setting exists in more thO and set differently in different GPOs, then the last applying GPO setting overwrites the others. SYSVOL has no relationship with local policy, it is an infrastructural directory that holds GPO setting for the domain, site, OUs in Active Directory and sysvol directories are replicated automatically via DFS_R replication mechanism between ONLY domain controllers of the same domain.