A high speed, microcomputer based, Fibre Channel compatible and fault tolerant information processing and mass storage system especially suited for information servers and application servers. A unique and extremely versatile system architecture, including a dual loop arbitrated, Fibre Channel capable, multiple-fault tolerant, hot-swappable mass storage disk array, permits combinations of servers and mass storage arrays which can be tailored for a wide variety of applications and which can be configured with emphasis on the system characteristics such as redundancy, speed, processing capability, storage capability, and the like, as desired. A unique backplane and/or midplane arrangement for connecting the system components allows for easy and, in most cases, on-line field upgrading and/or service and at the same time provides for the very effective cooling of components, particularly those such as disk drives which tend to produce a lot of heat.