Patent ID: 8402212
Filing Date: 2013-03-19
Classification: G06F

Abstract:
1. A storage system, comprising: a plurality of expanders to be connected to a plurality of storage mediums; a plurality of cascades connected respectively to a prescribed number of expanders among the plurality of expanders; and a plurality of control units for respectively controlling the plurality of cascades; the storage system further comprising: an inter-cascade link configured by connecting expanders at an end that is different from the side to be controlled to the control units of the plurality of cascades, wherein each of the plurality of control units manages the inter-cascade link as a logically connected state or a logically disconnected state, wherein each control unit comprises a detection unit for detecting abnormalities in access, wherein, when the detection unit detects an abnormality in the access of expanders or between the respective expanders, the control unit sets the inter-cascade link to a logically connected state so that the control unit can access to the expanders or between the respective expanders in which abnormalities have been detected by the detection unit, and wherein, upon detecting that the abnormality has been eliminated with the detection unit, the control unit sets the inter-cascade link to a logically disconnected state, wherein data to be stored is stored redundantly in the plurality of storage mediums configured from the same redundant group, wherein the same redundant group is stored in corresponding storage mediums each being positioned on opposite sides of a point of symmetry between one cascade and another cascade, wherein, when the plurality of cascades are two cascades, the storage mediums in one of the cascades are each assigned an identifier of a redundant group and said identifiers of the one cascades are assigned in ascending order in relation to the number of expanders to be passed through from the control units upon accessing that storage medium; and wherein the storage mediums in the other cascade among the plurality of cascades are each assigned an identifier of a redundant group and said identifiers of the one cascades are assigned in descending order in relation to the number of expanders to be passed through from the control units upon accessing that storage medium.