Striping in large tape libraries

Abstract

Data striping is a technique for increasing the throughput and reducing the response time of large accesses to a storage system. In this paper, we evaluate the effectiveness of applying striping concepts to large tape libraries. Striping in tape libraries is being used with success for applications such as backup and scientific data collection, where data access patterns are strictly sequential. In this paper, we evaluate striped performance for randomly distributed accesses to the tape library. We believe such operations will be characteristic of future tertiary storage databases using large objects, such as on-line libraries and multimedia databases. Using an event-driven simulator, we show that striped large tape libraries perform poorly for this random workload because striping causes contention for the small number of readers and robot arms in these libraries. Increasing the number of readers results in better striped performance. We also examine how the effectiveness of striping ...