An ATLAS Software Release is a software collection to perform computing within the scope of the ATLAS experiment at the Large Hadron Collider (CERN, Geneva). This documentation describes how to perform computing with an ATLAS Software Release in Amazon’s Elastic Computing Cloud EC2. Therefore, an Amazon Machine Image (AMI) on the basis of the standard ATLAS platform Scientific Linux 4 (SL4) was created. The development is shown in detail. A proof-of-principle job system was developed. Jobs can use the software in the normal way. The output of a job is exported to Amazon’s Simple Storage Service S3, before the corresponding virtual machine in the cloud is terminated. Job status information is transferred to Amazon’s SimpleDB service. Job sessions are controlled and monitored by a client using Python scripts implementing the Amazon Web Services API via the boto library working together with scripts embedded in the SL4 AMI. The experience with setting up and operating the described system using standard ATLAS job transforms is reported.
It is shown, that ATLAS Cloud Computing is a promising substitute for classical ATLAS Computing. The basic services a computing cloud should deliver for ATLAS Cloud Computing were elaborated. The benefit of a general Cloud Computing API with different possible clouds at the back end is discussed. It seems possible to set up an EC2 style cloud in the future, so that the advantages of Cloud Computing would be available for the price of own hardware.
