Storage system and disconnecting method of a faulty storage device

A storage system which accesses a plurality of storage devices in response to data access requests from a request device, comprising:

• a plurality of storage devices;
• at least one controller which controls said plurality of storage devices;
• a pair of loops, in which information circulates in a single direction, for exchanging information among said controller and said plurality of storage devices;
• a plurality of first switches, provided in one of said loops, to connect one of said pair of loops to said plurality of storage devices;
• a plurality of second switches, provided in another one of said loops, to connect another one of said pair of loops to said plurality of storage devices;
• a first device control unit, connected by a first path to said controller and connected by a second path to said storage devices, and which operate said plurality of first switches;
• and
• a second device control unit, connected by a third path to said controller and connected by a fourth path to said storage devices, and which operate said plurality of second switches.
• said first, second, third and fourth paths comprising physical paths separated from said pair of loops,
• wherein said controller has a first disconnect mode for issuing a disconnect instruction to any one of said first and second device control units via said first path or said third path;
• and a second disconnect mode for issuing a disconnect instruction to any one of said first and second device control units via any one of said pair of loops, said storage device, and said second path or said fourth path,
• wherein said controller switches all first or second switches in said one of a pair of loops into a bypass state and switches the switches of said storage devices having said second path to said one loop into a connection state by executing said first disconnect mode when detecting the fault of the storage device from a response when accessing said storage device through said one of loops, and then identifies said faulty storage device and bypasses said faulty storage device from said loop by executing said second disconnect mode.

A faulty storage device disconnecting method for disconnecting a faulty storage device in a storage system in which a plurality of storage devices connected by a pair of loops are accessed in response to data access requests from a request device, comprising the steps of:

• issuing a disconnect instruction from a controller to a first device control unit for operating a plurality of first switches to connect said plurality of storage devices to one of said pair of loops when detecting a fault of said one of said pair of loops;
• and
• issuing a disconnect instruction from said controller to a second device control unit for operating a plurality of second switches to connect said plurality of storage devices to another one of said pair of loops when detecting a fault of said another one of said pair of loops;
• and
• disconnecting a faulty storage device from said loops by using a first disconnect mode, in which said disconnect instruction is issued to said first device control unit via a first path connecting said controller and said first device control unit, and a second disconnect mode, in which said disconnect instruction is issued to said first device control unit via said another one of said loops, said storage device, and a second path connecting said storage devices and said first device control unit,
• wherein said disconnecting step comprises the steps of:
• executing one of said first disconnect mode and said second disconnect mode when detecting the fault of the storage device from a response when accessing said storage device through said one of loops;
• and
• executing another of said first disconnect mode and said second disconnect mode when detecting a faulty disconnect of said faulty storage device by executing said one of said first disconnect mode and said second disconnect mode.

A faulty storage device disconnecting method for disconnecting a faulty storage device in a storage system in which a plurality of storage devices connected by a pair of loops are accessed in response to data access requests from a request device, comprising the steps of:

• issuing a first disconnect instruction from a controller to a first device control unit for operating a plurality of first switches to connect said plurality of storage devices to one of said pair of loops when detecting a fault of said one of said pair of loops, and issuing a disconnect instruction from said controller to a second device control unit for operating a plurality of second switches to connect said plurality of storage devices to another one of said pair of loops when detecting a fault of said another one of said pair of loops;
• and
• disconnecting a faulty storage device from said loops by using a first disconnect mode, in which said first disconnect instruction is issued to said first device control unit via a first path connecting said controller and said first device control unit, and a second disconnect mode, in which said first disconnect instruction is issued to said first device control unit via said another one of said loops, said storage device, and a second path connecting said storage devices and said first device control unit,
• wherein said disconnecting step comprises the steps of:
• a switching all first or second switches in said one of a pair of loops into a bypass state and moreover switching the switches of said storage devices having said second path to said one loop into a connection state by executing said first disconnect mode when detecting the fault of the storage device from a response when accessing said storage device through said one of loops;
• and
• identifying said faulty storage device and bypassing said faulty storage device from said loop by executing said second disconnect mode.