A user store is the database where information about the users and user roles is stored, including log-in name, password, first name, last name, and e-mail address. The user stores of all WSO2 Carbon-based products are embedded H2 databases except for WSO2 Identity Server, which has an embedded LDAP as its user store. In Carbon, permissions are stored in a separate database called the User Management database. The default User Management database is H2, but you can connect to external user stores as well.
For enterprise production environments, we do not recommend this the embedded H2 database as a user store.
Also, WSO2 Identity Server is shipped with a default embedded ApacheDS. However, in a production environment, it is recommended to use an LDAP like OpenLDAP, due to scalability issues that exist with Apache DS.