Red Hat Enterprise Linux 7.0 includes samba packages upgraded to the latest upstream version, which introduce several bug fixes and enhancements, the most notable of which is support for the SMB3 protocol in the server and client tools.
Additionally, SMB3 transport enables encrypted transport connections to Windows servers that support SMB3, as well as Samba servers. Also, Samba 4.1.0 adds support for server-side copy operations. Clients making use of server-side copy support, such as the latest Windows releases, should experience considerable performance improvements for file copy operations.
The updated samba packages remove several already deprecated configuration options. The most imporant are the server roles security = share and security = server. Also the web configuration tool SWAT has been completely removed. More details can be found in the Samba 4.0 and 4.1 release notes:
Note that several tdb files have been updated. This means that all tdb files are upgraded as soon as you start the new version of the smbd daemon. You cannot downgrade to an older Samba version unless you have backups of the tdb files
For more information about these changes, refer to the Release Notes for Samba 4.0 and 4.1 mentioned above.