Abstract: A storage system has a storage controller and a RAID group. The storage controller has policy management information such that one failure recovery process among a plurality of differing failure recovery processes is associated with each RAID group, and when an error in a command issued to a RAID group is detected, the failure recovery process associated with the RAID group to which the command was issued is specified on the basis of the policy management information, and the specified failure recovery process is executed.

Abstract: A storage system has a storage controller and a RAID group. The storage controller has policy management information such that one failure recovery process among a plurality of differing failure recovery processes is associated with each RAID group, and when an error in a command issued to a RAID group is detected, the failure recovery process associated with the RAID group to which the command was issued is specified on the basis of the policy management information, and the specified failure recovery process is executed.

Abstract: A storage apparatus and tier control method capable of executing hierarchical control based on variable performance of SSDs are suggested. With a storage apparatus equipped with a plurality of drives composed of flash memories, the storage apparatus includes a controller for hierarchically controlling storage areas provided by the plurality of drives by classifying the storage areas into a plurality of tiers with different performances and managing them, wherein the controller: decides a first tier, to which each of the drives should belong, based on performance of the drive; decides to change the tier, to which the drive should belong, from the first tier to a second tier different from the first tier based on the drive's performance, which varies depending on property of the drive; and changes the tier, to which the drive determined to change its tier should belong, from the first tier to the second tier.

Abstract: A storage apparatus and tier control method capable of executing hierarchical control based on variable performance of SSDs are suggested. With a storage apparatus equipped with a plurality of drives composed of flash memories, the storage apparatus includes a controller for hierarchically controlling storage areas provided by the plurality of drives by classifying the storage areas into a plurality of tiers with different performances and managing them, wherein the controller: decides a first tier, to which each of the drives should belong, based on performance of the drive; decides to change the tier, to which the drive should belong, from the first tier to a second tier different from the first tier based on the drive's performance, which varies depending on property of the drive; and changes the tier, to which the drive determined to change its tier should belong, from the first tier to the second tier.

Abstract: In storage subsystems, due to the significant increase in HDD capacity, the time for executing online verification is elongated, affecting accesses from the host computer. By comprehending the status of accesses to the HDD, the sections where error has occurred and the status of restoration thereof, it becomes possible to detect defective or error sections efficiently at an early stage, according to which the reliability and access performance of the storage subsystem can be improved. The present storage subsystem executes one or more of the following processes: (M1) intensive verification of a circumference of an error LBA, (M2) an area-based prioritized verification, and (M3) continuous verification performed for a long period of time to (V1) an area in which error has occurred via IO access, (V2) a highly accessed area, and (V3) during a period of time when IO access is low.

Abstract: In storage subsystems, due to the significant increase in HDD capacity, the time for executing online verification is elongated, affecting accesses from the host computer. By comprehending the status of accesses to the HDD, the sections where error has occurred and the status of restoration thereof, it becomes possible to detect defective or error sections efficiently at an early stage, according to which the reliability and access performance of the storage subsystem can be improved. The present storage subsystem executes one or more of the following processes: (M1) intensive verification of a circumference of an error LBA, (M2) an area-based prioritized verification, and (M3) continuous verification performed for a long period of time to (V1) an area in which error has occurred via IO access, (V2) a highly accessed area, and (V3) during a period of time when IO access is low.

Abstract: A system according to the invention reads/writes data by using a memory device performing a wear leveling. A host 4 reads/writes data from/in a flash memory device 2. A first protection code BC is added to the end of a logical block for every logical block of 512 bytes. A second protection code FC is added to the head of the logical blocks. The first protection code BC and the second protection code FC are configured to include data for specifying the logical address. When data is read from the flash memory device 2, the logical address obtained from the first protection code BC is compared to the logical address obtained from the second protection code. When both logical addresses are identical, it is determined that correct data is read.

Abstract: A system according to the invention reads/writes data by using a memory device performing a wear leveling. A host 4 reads/writes data from/in a flash memory device 2. A first protection code BC is added to the end of a logical block for every logical block of 512 bytes. A second protection code FC is added to the head of the logical blocks. The first protection code BC and the second protection code FC are configured to include data for specifying the logical address. When data is read from the flash memory device 2, the logical address obtained from the first protection code BC is compared to the logical address obtained from the second protection code. When both logical addresses are identical, it is determined that correct data is read.