Abstract: Logical hierarchies include an append hierarchy in a storage device. The storage device writes user data received in the append hierarchy to a free area, select a garbage collection operation mode for a first logical area in the append hierarchy from operation modes including first and second operation modes. Conditions of executing the garbage collection in the first operation mode include a capacity of the free area in the append hierarchy being less than a threshold, and an amount of garbage that is invalid data after update in the first logical area being equal to or greater than a threshold. Conditions of executing the garbage collection in the second operation mode include the amount of garbage in the first logical area being equal to or greater than a threshold value, while excluding the condition of the capacity of the free area in the append hierarchy.

Abstract: Provided is a storage system including a plurality of controllers. The storage system adopts a write-once data storage system and can implement high Input/Output (I/O) processing performance while ensuring data consistency when a failure occurs. Before metadata duplication, recovery data including information necessary for performing roll forward or roll back is stored in each controller, and then the metadata duplication is performed. A recovery data storage processing and the metadata duplication are offloaded to a hardware accelerator.

Abstract: A storage device manages data stored in a storage drive in a plurality of logical hierarchies. The plurality of logical hierarchies include a writing hierarchy above a hierarchy of a parity group including a plurality of storage drives. The storage device writes received host data in a free area in the writing hierarchy. In the data recovery process for replacing a failure storage drive with a new storage drive, the storage device executes the garbage collection process on a first logical area in the writing hierarchy associated with the first parity group including the failure storage drive. In the garbage collection process, valid data is selected from the first logical area and copied to a second logical area associated with a second parity group different from the first parity group.

Abstract: Provided is a storage system including a plurality of controllers. The storage system adopts a write-once data storage system and can implement high Input/Output (I/O) processing performance while ensuring data consistency when a failure occurs. Before metadata duplication, recovery data including information necessary for performing roll forward or roll back is stored in each controller, and then the metadata duplication is performed. A recovery data storage processing and the metadata duplication are offloaded to a hardware accelerator.

Abstract: Provided is a storage system including a plurality of controllers. The storage system adopts a write-once data storage system and can implement high Input/Output (I/O) processing performance while ensuring data consistency when a failure occurs. Before metadata duplication, recovery data including information necessary for performing roll forward or roll back is stored in each controller, and then the metadata duplication is performed. A recovery data storage processing and the metadata duplication are offloaded to a hardware accelerator.

Abstract: A storage system includes controllers, physical storage devices, and logical storage devices to which storage areas are assigned from the physical storage devices. The controllers each have the physical storage device being different from that of each other and the host connected thereto being different from that of each other, and are each able to access the physical storage device and the host that are not connected thereto, through another controller. Any one of the controllers has an ownership to process an access request concerning the logical storage device. At least one controller determines that the ownership is caused to be moved among the controllers, based on an index of accesses to the physical storage device that includes the storage area to be assigned to the logical storage device and an index of accesses to the host that accesses the logical storage device.

Abstract: A storage system includes controllers, physical storage devices, and logical storage devices to which storage areas are assigned from the physical storage devices. The controllers each have the physical storage device being different from that of each other and the host connected thereto being different from that of each other, and are each able to access the physical storage device and the host that are not connected thereto, through another controller. Any one of the controllers has an ownership to process an access request concerning the logical storage device. At least one controller determines that the ownership is caused to be moved among the controllers, based on an index of accesses to the physical storage device that includes the storage area to be assigned to the logical storage device and an index of accesses to the host that accesses the logical storage device.