Patent ID: 8499098
Filing Date: 2013-07-30
Classification: G06F

Abstract:
1. A storage system comprising: a first storage device, which is coupled to a host computer via a first communication network; a second storage device, which is coupled to the host computer via the first communication network, and, in addition, is communicably coupled to the first storage device; a third storage device, which is coupled to the first storage device and the second storage device via a second communication network; and a management computer, which is communicably coupled to the host computer, the first storage device, the second storage device and the third storage device, wherein the first storage device comprises: a first logical volume, which is provided so as to be able to be used by the host computer; a first cache memory for temporarily storing data of the first logical volume; and a plurality of first communication paths, which are provided on the first communication network for coupling the host computer and the first logical volume, the second storage device comprises: a second logical volume, which is provided so as to be able to be used by the host computer, and which forms a copy pair with the first logical volume; a second cache memory for temporarily storing data of the second logical volume; and a plurality of second communication paths, which are provided on the first communication network to couple the host computer and the second logical volume, the third storage device comprises a third logical volume, which is associated with the first logical volume and the second logical volume, has a real storage area that is commonly associated with a virtual storage area of the first logical volume and a virtual storage area of the second logical volume, and stores data written into the first logical volume and the second logical volume, the management computer, based on a status of the first communication network and a status of the second communication network, sets a first priority for each of the first communication paths and a second priority for each of the second communication paths, and notifies an administrator who uses either the host computer or the management computer of the set first priorities and the set second priorities respectively, wherein the management computer sends and stores the set respective first priorities in the first storage device, and, in addition, sends and stores the set respective second priorities in the second storage device, the first storage device, in a case where the host computer queries about the statuses of the respective first communication paths, notifies the host computer of the respective first priorities, the second storage device, in a case where the host computer queries about the statuses of the respective second communication paths, notifies the host computer of the respective second priorities, the host computer selects a communication path to be used based on the respective first priorities notified from the first storage device and the respective second priorities notified from the second storage device, the management computer, based on a communication path assessment table showing the relationship between the respective first priorities, the respective second priorities, and assessment values, which are computed for the respective first communication paths and the respective second communication paths, sets the respective first priorities and the respective second priorities so as to prioritize the communication path currently being used from among the respective first communication paths and the respective second communication paths, wherein a first assessment table and a second assessment table are included in the respective communication path assessment tables, the management computer, in a case where the cache hit ratio denoting what proportion of data, which is requested by the host computer, is stored in the first cache memory, is less than a predetermined value, selects the first assessment table included in the respective communication path assessment tables, and in a case where the cache hit ratio is equal to or greater than the predetermined value, selects the second assessment table included in the respective communication path assessment tables, wherein the first assessment table is configured such that the priority of a first active communication path, which is an active side communication path that is currently being used from among the respective first communication paths and the respective second communication paths, and for which both the status of the first communication network and the status of the second communication network are normal, constitutes the highest priority, such that the priority of a first passive communication path, which is a passive side communication path that is not currently being used from among the respective first communication paths and the respective second communication paths, and for which both the status of the first communication network and the status of the second communication network are normal, constitutes the lowest priority, and such that another communication path other than the first active communication path and the first passive communication path is blocked, and the second assessment table is configured such that the priority of a first active communication path, which is an active side communication path, and for which both the status of the first communication network and the status of the second communication network are normal, constitutes the highest priority, such that the priority of a second active communication path, which is an active side communication path, and for which the status of the first communication network is normal and an intermittent failure has occurred in second communication network, constitutes the secondary highest priority, such that the priority of a first passive communication path, which is a passive side communication path, and for which both the status of the first communication network and the status of the second communication network are normal, constitutes the tertiary highest priority, such that the priority of a second passive communication path, which is a passive side communication path, and for which the status of the first communication network is normal and an intermittent failure has occurred in second communication network, constitutes the lowest priority, and such that another communication path other than the first active communication path, the second active communication path, the first passive communication path and the second passive communication path is blocked.