syncrepl

Syncrepl is a replication mechanism commonly used with LDAP servers, particularly OpenLDAP. It enables the synchronization of directory data between multiple LDAP servers, ensuring consistency across a distributed environment. Syncrepl operates by having one or more consumer servers connect to a provider server and receive change logs. These changes are then applied to the consumer's local replica of the directory.

There are two primary modes for syncrepl: "1-way" and "multi-master". In 1-way replication, a single provider server is designated as the source of truth, and changes flow from this provider to one or more consumers. This is a common setup for read-heavy environments where data updates occur in a central location. Multi-master replication, on the other hand, allows changes to be made on any server in the replicated group, with those changes then being propagated to all other servers. This provides higher availability and can distribute write load.

The configuration of syncrepl involves defining connection parameters for the provider, the replication context (the part of the directory tree to be replicated), and the criteria for what changes should be synchronized. Security is typically handled through TLS/SSL connections and authentication mechanisms. Syncrepl is a powerful tool for building resilient and scalable directory services, facilitating high availability, load balancing, and disaster recovery.