Parallel file striping on optical jukebox servers

In the near future, large digital media servers are expected to offer storage capacities in the order of petabytes. Servers made of clusters of PCs connected to jukeboxes may represent an interesting alternative compared with servers made of arrays of magnetic disks. However, due to disk exchange overhead, higher seek times and lower data transfer rates, access to data located on optical disks is significantly slower than access to data located on magnetic disks. In the present contribution, we analyze the benefits and limitations of striping files across multiple optical disks in order to speedup the retrieval of large pieces of information. We also show that server applications requiring both computer power and I/O bandwidth may be distributed over several processing nodes and access files striped over multiple optical disks. For such applications, as long as disk exchanges are not necessary, a predictable speedup can be obtained by ensuring a high enough number of server computers, optical disk drive units, and enough communication bandwidth.