This paper proposes a new high-performance paradigm for accessing
removable media such as tapes and especially magneto-optical disks.
In high-performance computing, striping of data across multiple
devices is a common means of improving transfer rates. Striping has
been used very successfully for fixed magnetic disks, improving
overall system reliability as well as throughput. It has also been
proposed as a solution for providing improved bandwidth for tape and
magneto-optical subsystems. However, striping of removable media has
shortcomings, partciularly in the areas of latency to data and
restricted system configurations, and is suitable primarily for very
large I/Os. We propose that for fine-grained media, an alternative
access method, media pipelining, may be used to provide high bandwidth
for large requests while retaining the flexibility to support
concurrent small requests and different system configurations. Its
principal drawback is high buffering requirements in the host computer
or file server.
This paper discusses the possible organization of such a system,
including the hardware conditions under which it may be effectibe, and
the flexibility of configuration. Its expected performance is
discussed under varying workloads, including large single I/Os and
numerous smaller ones. Finally, a specific system incorporating a
high-transfer-rate magneto-optical disk drive and autochanger is
discussed.