Azure File Sync is an Azure service that enables customers to centralize file shares in Azure files, while keeping the flexibility, performance, and compatibility of a local file server. Azure File Sync enables Windows Servers to perform a quick cache of an Azure file share. Any protocol that's available on Windows Server to access data locally, including SMB, NFS and FTPS, can be used. Those caches have no limit and customers can have as many local file server caches as they need. 

To use Azure File Sync, you need at least Windows Server 2012 R2 or later and PowerShell 5.1 installed on the server. Azure File Sync supports also cloud tiering, ACL replication between cloud and on-premise, as well as the integration of Azure AD identity management.