Storage Management and Access in WLHC Computing Grid

One of the big challenges in Grid computing is storage management and access. Several solutions exist to store data in a persistent way. In this work we describe our contribution within the Worldwide LHC Computing Grid project. Substantial samples of data produced by the High Energy Physics detectors at CERN are shipped for initial processing to specific large computing centers worldwide. Such centers are normally able to provide persistent storage for tens of Petabytes of data mostly on tapes. Special physics applications are used to refine and filter the data after spooling the required files from tape to disk. At smaller geographically dispersed centers, physicists perform the analysis of such data stored on disk-only caches. In this thesis we analyze the application requirements such as uniform storage management, quality of storage, POSIX-like file access, performance, etc. Furthermore, security, policy enforcement, monitoring, and accounting need to be addressed carefully in a Grid environment. We then make a survey of the multitude of storage products deployed in the WLCG infrastructure, both hardware and software. We outline the specific features, functionalities and diverse interfaces offered to users. Among the other storage services, we describe StoRM, a storage resource manager that we have designed and developed to provide an answer to specific user request for a fast and efficient Grid interface to available paral lel file systems. We propose a model for the Storage Resource Management protocol for uniform storage management and access in the Grid. The black box testing methodology has been applied in order to verify the completeness of the specifications and validate the existent implementations. We finally describe and report on the results obtained.