tdbsam
The tdbsam backend provides an ideal database backend for local servers, servers that do not need built-in database replication, and servers that do not require the scalability or complexity of LDAP. The tdbsam backend includes all of the smbpasswd database information as well as the previously-excluded SAM information. The inclusion of the extended SAM data allows Samba to implement the same account and system access controls as seen with Windows NT/2000/2003-based systems.
The tdbsam backend is recommended for 250 users at most. Larger organizations should require Active Directory or LDAP integration due to scalability and possible network infrastructure concerns.
ldapsam
The ldapsam backend provides an optimal distributed account installation method for Samba. LDAP is optimal because of its ability to replicate its database to any number of servers using the OpenLDAP slurpd daemon. LDAP databases are light-weight and scalable, perfect for most organizations, especially large enterprises. LDAP is definitely the "wave of the future" with regards to Samba. Improvements to LDAP are constantly being added into Samba such as easing installation and configuration issues.
mysqlsam
The mysqlsam backend uses a MySQL-based database backend. This is useful for sites that already implement MySQL.
xmlsam
The xmlsam backend uses account and password data that are stored in an XML formatted file. This method can be useful for migration of different backend databases or backups.
