Dovecot Cluster Architecture


This is a Dovecot Pro v3.0 feature.

New in version 3.0.0 (Pro).

The Dovecot Cluster Architecture in v3.0 replaces the director component in older Dovecot versions with a new cluster service. The cluster service provides:

  • Load balancer between Dovecot Proxies and Backends

  • User-stickiness to backends

  • High availability for backends and other sites

  • Load redistribution / user moving

  • Multi-site support

Users are always attempted to be accessed only via a single backend at a time. This allows caching to work efficiently. When using object storage and multiple sites, it’s possible that the user is accessed simultaneously by multiple sites when the sites’ networks don’t see each others (split brain). The obox format handles this by eventually merging the changes and moving the user handling back to a single site soon after the split brain is over.