Commissioning and Performance of the ATLAS Inner Detector with proton-proton Collisions at the LHC

The ATLAS Inner Detector is a composite tracking system consisting of silicon pixels, silicon strips and straw tubes in a 2 T magnetic field. Its installation was completed in August 2008 and the detector has taken part in datataking with colliding LHC beams. Utilising collision data we present studies of the individual sub-systems, which include measurements of the Lorentz angle, timing, noise characteristics and cluster reconstruction efficiency. We also report results of the post collision alignment of the detector geometry and probe the agreement between data and simulation in the early stages of track reconstruction at ATLAS.