ATLAS detector performance status and operations, improvements during shutdown, and 2011 data taking

After the successful 2010 LHC run, where the ATLAS detector recorder 45$mathrm{pb^{-1}}$ of proton-proton collision data with 93.6% data taking efficiency and during the recent LHC shutdown period, ATLAS performed vital maintenance and improvements on the various sub-detectors. Maintenance on the Muon Spectrometer included repairs on the readout system as well as updates and leak checks in the gas system. Six TGC chambers have been also replaced. For the Calorimeters, repairs were carried out on the front-end electronics and power supplies to recover detector coverage that have been lost since the last maintenance period. Repairs were also performed on the Inner Detector, but at a smaller scale. Finally the ALFA luminosity detector was installed along the beam line and is being commissioned. This talk summarizes the above repairs and their expected improvement for physics performance and reliability of the ATLAS for the 2011 LHC run.