ATLAS detector with cosmic rays and expected performance with early LHC data

After 20 years from the first workshop in Lausanne, the integration and installation at CERN of the ATLAS detector was completed during summer 2008. The cosmic data taken since then have been very useful in commissioning of the subsystems, of the controls and of the trigger and data acquisition. Some of the results are shown in this talk. The talk will also outline the expected performance of the detector with the first LHC collision data in the end of 2009.