Abstract: A higher-level system that inputs and outputs data to/from a storage area including one or more logical areas respectively provided from one or more NVM drives manages the storage area, and manages a plurality of chunks that are a plurality of areas forming the storage area, each of the chunks being a unit of data input/output and being an non-overwritable area. Each of the plurality of chunks has the same chunk size, and each of the plurality of chunks includes a part of each of one or more logical areas. Each of the plurality of chunks includes, for each of the one or more NVM drives, all or part of one or more logical blocks that are one or more ranges corresponding to one or more physical blocks, respectively, but does not include at least a part of a logical block that is entirely or partially included in another chunk.

Abstract: A higher-level system that inputs and outputs data to/from a storage area including one or more logical areas respectively provided from one or more NVM drives manages the storage area, and manages a plurality of chunks that are a plurality of areas forming the storage area, each of the chunks being a unit of data input/output and being an non-overwritable area. Each of the plurality of chunks has the same chunk size, and each of the plurality of chunks includes a part of each of one or more logical areas. Each of the plurality of chunks includes, for each of the one or more NVM drives, all or part of one or more logical blocks that are one or more ranges corresponding to one or more physical blocks, respectively, but does not include at least a part of a logical block that is entirely or partially included in another chunk.

Abstract: According to one aspect of the present invention, the storage system has a storage controller and a plurality of storage devices. Each storage device calculates its degradation level based on an error bit count (number of correctable errors that have occurred during read), and transmits the same to the storage controller. By calculating the life of each RAID group based on the received degradation levels of the respective storage devices, the storage controller specifies the RAID group predicted to reach its life before achieving a target service life (target life), and migrates the data stored in the specified RAID group to a different RAID group.