Storage redundancy may be resynchronized without determining a snapshot difference. A storage component (210) owning a volume (122) can maintain current and expected generation numbers (212, 214) based on modification requests received and modification requests that a backup component (220) acknowledges completing. The backup (220) can maintain current and expected generation numbers (222, 224) based on modification requests received and applied to a backup volume (124). If either component (210, 220) fails and later returns to service, differences between the owner's current and expected generation numbers (212, 214) and the backup's current and expected generation numbers (222, 224) indicate which modification requests may have been missed and need to be reconstructed to restore synchronization.