In large pot, combine pancetta and olive oil. Cook until the pancetta is lightly browned about 10 minutes. Add celery, carrots and onion. Cook until all vegetable are browned about 10 minutes. Stir in garlic. Drain beans and add them to the pot with 2 quarts of water. Bring to a simmer over low heat. Cook for 1 hour and 15 minutes. Coarsely mash with the back of a spoon. Add barley, salt and pepper. Cook for 30 minutes or until barley is tender. Stir frequently to prevent sticking. Add a little water is it becomes to thick. Stir in parsley and serve.