Patent ID: 6401170
Filing Date: 2002-06-04
Classification: G06F

Abstract:
A redundant RAID system comprising:N host computers and M storage array controllers (SACs), each host computer and each SAC linked to each other host computer and each other SAC by loop connecting means, each having a unique address, and each able to communicate with each member of the loop, wherein N is greater than M, and M is equal to or greater than 2; each host computer associated with one SAC and each SAC connected to an array of storage units comprising one or more channels of storage units, each channel of storage units having a multiplicity of storage units, each storage unit having dual ports, by a loop connector using one port on each storage unit, and controlling these storage units as primary SAC; each SAC also connected to another array of storage units, each storage unit having dual ports, by another loop connector using a second port, and able to control these storage units as secondary SAC; each array of storage units thereby controlled by a primary SAC and potentially controlled by a secondary SAC; an array of storage units, the combination of an array's primary SAC, secondary SAC and array of storage units termed a storage array set; whereby each SAC is a member of two storage array sets, as primary SAC of a first storage array set, and as secondary SAC of a second storage array set; an interface chip attached to each SAC, each interface chip also connected to each host computer and to each SAC by loop connecting means, each interface chip able to assess the status of the SAC to which it is attached and associated host computer or host computers, and able to communicate with the secondary SAC of its storage array set; each secondary SAC able to assume the identity of the primary SAC of its storage array set in the event of the failure of the primary SAC of its storage array set or failure of the associated host computer or computers; whereby the failure of the primary SAC of a storage array set or associated host computer causes the secondary SAC of the storage array set to assume the control of the array of storage units of the storage array set.