Abstract: An object of the present invention is to allow access to a plurality of logical devices regardless of the number of ports provided in a storage system and the number of logical devices that can be allocated to a single port, and thereby to improve the usability of the logical devices. A storage system comprises a plurality of logical devices, a target device which is the object of access from a computer, and a juke box system for allocating one of the plurality of logical devices to the target device. The juke box system changes the logical device that is allocated to the target device in accordance with a request from the computer.

Abstract: A storage system is utilized to its fullest storage capacity by setting a write inhibitive attribute to a desired storage area of the storage system. The storage system has a logical volume in which data is stored and a control device which controls access to the data stored in the logical volume. A first area of a desired size is set in the logical volume, and an access control attribute is set to the first area. In response to a request made by a computer to perform access to the logical volume, the control device notifies the computer that the control device does not perform the access when an area designated by the access request contains at least a part of the first area and the access control attribute set to the first area inhibits the type of the access requested.

Abstract: The present invention creates real data and parity data using plural hard disk control units without changing the number of disk adapters per hard disk control unit and distributes and stores data in a hard disk. While it is being requested that a disk utilization rate is increased maintaining the failure resistance of the hard disk, and, at the same time, to support the combination of the real data+parity data as before, it is desirable that the number of adapters that comprise the hard disk control unit should not be changed. According to the present invention, the number of hard disks that comprise RAID can be changed without changing the number of disk adapters per hard disk control unit.

Abstract: When data is copied from the first LDEV (logical device) to the second LDEV, the storage system sets security information of the same content as security information set for the first LDEV constituting the copy source for the second LDEV constituting the copy destination.

Abstract: The present invention carries out cache management in such a manner that the management region required for cache management does not increase, and neither does the performance decline. It is possible to combine use of both a hierarchical directory method and a hash directory method, in order to manage cache data. In a hierarchical directory method, the desired data is retrieved by referring to respective tables T1 to T7, in succession. In a hash directory method, the desired data is reached by referring to a hash table T10 and tables T4 to T7. Access conflicts between the respective methods are avoided by using the EDEV number and a portion of the VDEV number for a hash key. By combining use of both of these methods, it is possible to respond to cases where the storage capacity of the storage system has been increased, without having to raise the management region, and without causing a decline in performance.

Abstract: The present invention partitions a cache region of a storage subsystem for each user and prevents interference between user-dedicated regions. A plurality of CLPR can be established within the storage subsystem. A CLPR is a user-dedicated region that can be used by partitioning the cache region of a cache memory. Management information required to manage the data stored in the cache memory is allocated to each CLPR in accordance with the attribute of the segment or slot. The clean queue and clean counter, which manage the segments in a clean state, are provided in each CLPR. The dirty queue and dirty counter are used jointly by all the CLPR. The free queue, classification queue, and BIND queue are applied jointly to all the CLPR, only the counters being provided in each CLPR.

Abstract: An object of the present invention is to allow access to a plurality of logical devices regardless of the number of ports provided in a storage system and the number of logical devices that can be allocated to a single port, and thereby to improve the usability of the logical devices. A storage system comprises a plurality of logical devices, a target device which is the object of access from a computer, and a juke box system for allocating one of the plurality of logical devices to the target device. The juke box system changes the logical device that is allocated to the target device in accordance with a request from the computer.

Abstract: The present invention creates real data and parity data using plural hard disk control units without changing the number of disk adapters per hard disk control unit and distributes and stores data in a hard disk.