A high-performance storage system for the LHCb experiment

The LHCb experiment uses a single, high performance storage system to serve all kinds of storage needs: home directories, shared areas, raw data storage and buffer storage for event reconstruction. All these applications are concurrent and require careful optimisation. In particular for accessing the raw data in read and write mode, a custom light weight non-POSIX compliant file system has been developed. File serving is achieved by running several redundant file servers in an active active configuration with high availability capabilities and good performance. In this paper we describe the design and current architecture of this storage system. We discuss implementation issues and problems we had to overcome during the hitherto 18 months run-in period. Based on our experience we will also discuss the relative advantages and disadvantages of such a system over a system composed of several smaller storage systems. We also present performance measurements.