Modern processors are improving their speed at a very fast
rate. Memory design technologies try to keep pace with rapid evolution
of processors, and combined with caching techniques, they partly
succeed. However, disk speed is not improving at the same rate. On the
contrary, seek time, latency and bandwidth are almost the same as ten
years ago, and there is no much hope for the future. To prevent I/O to
become a significant slowdown in computer systems, alternative
solutions must be found. The paper presents an overview of software
and architectural techniques that try to overcome the I/O problem:
disk arrays (RAID), external-memory algorithms, interconnection
networks, parallel I/O, in their relation with uniprocessor and
multiprocessor architectures.