Starting with v1.9.0, Longhorn supports offline replica rebuilding, allowing degraded volumes to automatically rebuild replicas while detached.​

Global Setting offline-replica-rebuilding

• When enabled, Longhorn automatically initiates offline rebuilding for eligible volumes.​
• For more information, see settings.

Per-Volume Override

• You can override the global Offline Replica Rebuilding setting for each volume individually using the Longhorn UI or by running kubectl -n longhorn-system edit volume [volume-name] and modifying the Spec.OfflineRebuilding field.
• When set to enabled or disabled, this per-volume setting takes precedence over the global configuration. The default value is ignored.

Rebuilding Process

• When triggered, Longhorn attaches the volume without activating the frontend, rebuilds any missing replicas, and then detaches the volume upon completion.
• This process can be interrupted if the workload scales up.

Limitations

It does not apply to faulted volumes.​