ATLAS conditions database experience with the LCG COOL conditions database project

The size and complexity of LHC experiments raise unprecedented challenges not only in terms of detector design, construction and operation, but also in terms of software models and data access and storage. The nominal interaction rate of about 1 GHz at the design luminosity of 10³⁴ cm^-2 s^-1 must be reduced online by about seven orders of magnitude to an event rate of O(100) Hz going to mass storage, and consisting of several different streams, one of them entirely dedicated to the calibration. One of the most challenging tasks will be the storage of non-event data produced by calibration and alignment stream processes into the Conditions Database at the Tier0 (located at CERN). In this work, the ATLAS Calibration Streams and the Conditions Database will be described.