3.2. Replication concept#

The replication concept ensures the availability and consistency of the central domain database and contributes to its scalability. It is necessary to keep the domain data synchronized across all domain nodes because more than one domain node can have a copy of the central database. For example domain nodes can get disconnected or need to shutdown for maintenance.

Univention Corporate Server (UCS) implements the replication concept. The first domain node in the domain has the following tasks:

  • It writes domain object data to the database.

  • It monitors changes to the database.

  • It makes changes available to other domain nodes.

The other domain nodes have a read-only copy of the domain database.

The replication synchronizes a lot of data types. The following list names a few that domain nodes replicate and cannot cover all items:

  • User identities

  • Groups

  • Policies

  • Permissions

  • Information about systems

  • Information about printers

  • Information about file shares

The domain replication in UCS also ensures that the affected UCS systems run follow-up actions once the changes are replicated. The actions can comprise of, for example, updates to configurations of services and making the changes available to the users.