Multi-site failover

MinIO Sidekick supports automatic failover between multiple sites when backend servers become unavailable.

Configure multiple sites by passing separate groups of backend servers as command arguments. Sidekick tries sites in the order specified, routing traffic to the first site with healthy backends. When all backends in the active site fail health checks, the load balancer automatically switches to the next site.

Each site can contain multiple backend servers. Sidekick distributes requests across healthy backends within the active site using the configured load balancing algorithm. Only when all backends in a site become unhealthy does failover occur to the next site.

Site failover happens automatically when health checks detect that all backends in the current site are down. Sidekick immediately begins routing requests to the next configured site. No manual intervention or DNS changes are required.

When backends in the original site recover, the load balancer does not automatically fail back. The system continues using the current healthy site until it experiences failures. This prevents unnecessary site switching due to transient issues.

For multi-site deployments with read-write splitting, configure a read-only health check path for the failover site using --read-health-path. After failing over to the backup site, the load balancer only routes traffic when the site meets read quorum requirements. This prevents writes to degraded sites while still allowing read access during failures.