Dorsal augmentation -- rebuild. Can rib be harvested without taking away from the perichondrium?

Whether the perichondrium is left intact or not on a rib graft harvest has no influence on postoperative discomfort. That is best managed through the use of Exparel nerve blocks placed during the surgery. Rib grafts are used exclusively because larger volumes of cartilages are needed to accomplish the dorsal augmentation effect. They create far more graft volume than that of the ear, even if both sides are harvested.

Rhinoplasty is a surgery to improve the shape of the nose for breathing or appearance.Rib cartilage may be harvested to create structure and support to the nose. Perichondrium is the soft tissue that covers the rib cartilage. I find this soft tissue to be incredibly useful. It is readily available while harvesting the rib cartilage. Going to the ear adds a 3rd surgical site. Ear pain may be more than the rib discomfort. Rib pain is often related to the harvest technique. Smaller incisions that avoid cutting muscle have less pain. I would discuss this with a  rhinoplasty surgeon who understands these concepts regarding rib cartilage for a safe and happy outcome. Safety comes first. 

With cartilage grafting, it's the cartilage that's used.  The surrounding layer of perichondrium is either left behind (better) or taken with the cartilage and discarded.  With rib, leaving the perichondrium behind and closing it helps minimize pain and rebuild the cartilage.  Also, leaving part of the cartilage behind (as removing the whole piece of rib is usually not necessary anyway) helps stabilize and support the perichondrium repair.  This will help minimize pain, but pain cannot be avoided.