An Integrated Input/Output System for Multiprocessors

This paper presents some thoughts on problems arising in I/O systems. Firstly, the I/O needs of processors and multiprocessors and currently-used solutions are outlined. Next, for a multiprocessor architecture with Uniform Memory Access (UMA) a set of RAID-type disks is proposed whose access model is called Uniform Disk Access (UDA). A multiport disk cache with ultra-high-rate serial links carries out the interface between the multiprocessor and the set of disks, behaving as a virtual crossbar. In this way the bottleneck of I/Os can be eliminated, and their latency time can be considerably reduced. In this architecture data transfer is no longer performed using an SCSI bus but by using ultra-high-rate serial links, thus improving the transfer throughput of the I/O system-processor bus to a rate higher than or equal to that of the memory-processor bus. Out of this new approach a throughput of more than 1 Gbit/sec per processor is obtained.