Cook pasta until al dente in a large pot of boiling water with salt. Drain, reserving one cup of the pasta water.
Heat the oil in a large, deep skillet.
Add the pancetta pieces and cook over medium-high heat, stirring until themeat is lightly browned and most of the fat is rendered, 4 to 5 minutes.
Add the bucatini to the skillet and toss over moderate heat to coat with the fat and pancetta. Add ¾ cup of the reserved cooking water, the 1¼ cup of Pecorino, the pepper, and season with salt.
Toss the pasta until the sauce becomes very thick and creamy, 2 to 3 minutes; add more of the cooking water if necessary.