Longhorn currently does not support online replica rebuilding for volumes that use the V2 Data Engine. To overcome this limitation, an automatic offline replica rebuilding mechanism has been implemented. When a degraded volume is detached, Longhorn attaches the volume in maintenance mode and then initiates the rebuilding process. The volume is detached again once rebuilding is completed.

Settings

Global Settings

• offline-replica-rebuilding: Setting that allows rebuilding of offline replicas for volumes using the V2 Data Engine. This setting is enabled by default.

Volume-Specific Settings

• Volume.Spec.OfflineReplicaRebuilding: Setting that allows rebuilding of offline replicas for a specific volume. The default value is “ignored”, which allows Longhorn to apply the value of the global setting offline-replica-rebuilding. (Options: “ignored”, “disabled”, “enabled”)

Notice

Interruptions are possible during offline replica rebuilding because Longhorn ensures that critical tasks take precedence. When an application attempts to attach a volume that is undergoing rebuilding, the rebuilding task is canceled to make way for the higher-priority task.