06401170 is referenced by 45 patents.
The RAID system disclosed here uses arbitrated fiber channels or switch fabric to connect multiple host computers and storage array controllers (SAC). Each SAC is designated a primary SAC for an array of storage units, which it normally serves as controller, and as a secondary SAC for another array of storage units. A primary SAC, secondary SAC, and array of storage units is termed a storage unit set. When the primary SAC or associated host computer fails, the failure is detected by an interface chip, which causes the secondary SAC to assume the identify of the primary controller. Using system configuration information from the DASDs, the secondary SAC then controls the storage units of the storage unit set along with the storage units of which it is primary SAC. With this configuration, there is no need for switch apparatus between the storage arrays and there is no interference because dual ported storage units are used.