Beginning in Samba 4.1, a growing number of databases can use the NTDB format rather than TDB. If you enable this option these databases will default to a .ntdb extension rather than .tdb. If the .tdb file exists, it will automatically be converted to NTDB and renamed to .tdb.bak. Filenames explicitly specified in smb.conf will be respected (ie. the format will depend on the .ntdb or .tdb extension). no