fix(system backup/restore): disaster recovery (DR) volume

longhorn/longhorn-9330

Signed-off-by: Chin-Ya Huang <chin-ya.huang@suse.com>
(cherry picked from commit 9b73085)

controller/system_backup_controller.go

@@ -731,6 +731,13 @@ func (c *SystemBackupController) backupVolumesAlways(systemBackup *longhorn.Syst
 
 	volumeBackups := make(map[string]*longhorn.Backup, len(volumes))
 	for _, volume := range volumes {
+		// Don't need to create volume data backup for DR volumes since it will
+		// be restored from the source volume's backup.
+		if volume.Status.IsStandby {
+			c.logger.Infof("Skip backup for standby volume %v", volume.Name)
+			continue
+		}
+
 		backup, err := c.createVolumeBackup(volume, systemBackup)
 		if err != nil {
 			return nil, err

controller/system_rollout_controller.go

@@ -1906,7 +1906,7 @@ func (c *SystemRolloutController) restoreVolumes() (err error) {
 			restore.ResourceVersion = ""
 			restore.Spec.NodeID = ""
 
-			if restore.Status.LastBackup != "" {
+			if restore.Status.LastBackup != "" && !restore.Status.IsStandby {
 				restore.Spec.FromBackup = backupstore.EncodeBackupURL(restore.Status.LastBackup, restore.Name, c.backupTargetURL)
 				log = log.WithField("fromBackup", restore.Spec.FromBackup)
 			}