Abstract: In general, a DRAM is used as a cache memory, and when attempting to expand the capacity of the cache memory to increase the hit ratio, the DRAM is required to be physically augmented, which is not a simple task. Consequently, a storage system uses a page, which conforms to a capacity virtualization function (for example, a page allocatable to a logical volume in accordance with Thin Provisioning), as a cache area. This makes it possible to dynamically increase and decrease the cache capacity.

Abstract: A first virtual storage and a second virtual storage share an external LU (Logical Unit) inside an external storage. The first virtual storage comprises a first LU, which comprises multiple first virtual areas and conforms to thin provisioning, and an external capacity pool, which is a storage area based on the external LU, and which is partitioned into multiple external pages, which are sub-storage areas. The second virtual storage comprises a second LU, which comprises multiple second virtual areas and conforms to thin provisioning.

Abstract: A storage system is provided with a memory region, a cache memory region, and a processor. The memory region stores the time relation information that indicates a time relationship of a data element that has been stored into the cache memory region and that is to be written to the logical region and a snapshot acquisition point of time to the primary volume. The processor judges whether or not the data element that has been stored into the cache memory region is a snapshot configuration element based on the time relation information for the data element that is to be written to a logical region of a write destination that conforms to the write request that specifies the primary volume and that has been stored into the cache memory region.

Abstract: There are a loose coupling and a tight coupling as the coupling configurations for a first module and a second module. The loose coupling is a coupling configuration in which the first and second modules are coupled together by way of a front-end path, and the first module is not able to access a second storage resource. The tight coupling is a coupling configuration in which the first and second modules are coupled together by way of a back-end path, and the first module is able to access the second storage resource. A switch from the loose coupling to the tight coupling is performed using the following processing flow without the first and second modules being partitioned into respectively independent storage modules. Specifically, first, the first and second modules are coupled together by way of the back-end path, and next, the first module merges information denoted by second management information from the second storage resource with first management information via the back-end path.

Abstract: A first virtual storage and a second virtual storage share an external LU (Logical Unit) inside an external storage. The first virtual storage comprises a first LU, which comprises multiple first virtual areas and conforms to thin provisioning, and an external capacity pool, which is a storage area based on the external LU, and which is partitioned into multiple external pages, which are sub-storage areas. The second virtual storage comprises a second LU, which comprises multiple second virtual areas and conforms to thin provisioning.

Abstract: A second storage maps a migration source volume to a virtual volume of a migration destination volume according to storage virtualization technology. A host system including a host switches an access path from an access path to the migration source volume to an access path to the migration destination volume. The second storage executes copy processing of migrating, from the migration source volume to the migration destination volume, data in an assigned area of a virtual volume according to thin provisioning of the migration source volume based on the information contained in the first thin provisioning information in the first storage, and copying that data from the migration destination volume to a virtual volume according to thin provisioning of a copy destination volume in the second storage. The second storage associates the virtual volume of the copy destination volume with the migration destination volume in substitute for the original virtual volume.

Abstract: There are a loose coupling and a tight coupling as the coupling configurations for a first module and a second module. The loose coupling is a coupling configuration in which the first and second modules are coupled together by way of a front-end path, and the first module is not able to access a second storage resource. The tight coupling is a coupling configuration in which the first and second modules are coupled together by way of a back-end path, and the first module is able to access the second storage resource. A switch from the loose coupling to the tight coupling is performed using the following processing flow without the first and second modules being partitioned into respectively independent storage modules. Specifically, first, the first and second modules are coupled together by way of the back-end path, and next, the first module merges information denoted by second management information from the second storage resource with first management information via the back-end path.

Abstract: The present invention provides a storage system for migrating a storage apparatus. The storage system comprises the steps of: defining a logical volume on a storage apparatus to be migrated coupled to a first controller as a local volume coupled to a second controller; setting to receive an access targeted to the logical volume through an input/output port of the storage apparatus to be migrated, as the local volume coupled to the second controller; blocking the input/output port of the storage apparatus to be migrated; connecting the other input/output port of the storage apparatus to the second control apparatus.

Abstract: In a storage system which includes a plurality of microprocessors, it is desired to prevent delay in I/O responses due to synchronous' processing waiting for asynchronous processing, while still ensuring the throughput of asynchronous processing. In a plurality of microprocessors possessed by a controller, synchronous processors and asynchronous processors are mixed together. The synchronous processors are microprocessors whose duty is to perform synchronous processing and not to perform asynchronous processing. And the asynchronous processors are microprocessors whose duty is to perform asynchronous processing and not to perform synchronous processing.

Abstract: A plurality of global LDEV managed by a plurality of controller modules are provided above local LDEV under the control of each controller module. Each global LDEV is correlated to any of the plurality of local LDEV. The controller modules judge whether or not a local LDEV correlated to a global LDEV specified by an I/O request received from a host device or a first other controller module is a management target itself, and if the result of that judgment is affirmative, the controller modules access the local LDEV correlated to the specified global LDEV, while if the result of the judgment is negative, the controller modules transfer the received I/O request to a second other controller module.

Abstract: For a storage system having plural control units to which plural disk devices are connected, in the method for creating replication in a volume of the disk devices connected to different control units, when receiving update I/O of a replication source during an initial copy for replication, the reflection of update to the replication destination is performed on an extension of the same I/O. When a pair is divided after the completion of copying, the update position is retained on the differential bitmap disposed in the individual control units, and the differential bitmap is merged to one of the control units at a time of resynchronization to perform copy processing.

Abstract: This invention aims to improve the data guarantee performance of an external storage apparatus. Upon managing a storage extent of the external storage apparatus as a volume, a guarantee code corresponding to read or write access-target data is created with a guarantee code creation/confirmation unit, the created guarantee code is stored in the external storage apparatus, and, upon executing the read or write access to the storage extent of the external storage apparatus, the concordance of the guarantee code stored in correspondence with the access-target data and the guarantee code created from the access-target data is confirmed with the guarantee code creation/confirmation unit 206, whereby the access-target data can be guaranteed.

Abstract: For a storage system having plural control units to which plural disk devices are connected, in the method for creating replication in a volume of the disk devices connected to different control units, when receiving update I/O of a replication source during an initial copy for replication, the reflection of update to the replication destination is performed on an extension of the same I/O. When a pair is divided after the completion of copying, the update position is retained on the differential bitmap disposed in the individual control units, and the differential bitmap is merged to one of the control units at a time of resynchronization to perform copy processing.

Abstract: In a storage system having a plurality of control units each connected with a plurality of disk units, it is provided that a replication is created in the volume of the disk units connected to different control units. The replication creation unit of a given control unit creates a replication in the volume of the disk unit connected to other control units in such a manner that the original volume information, the replication volume information in the control unit and information on the other control units are registered as volume pair information. Based on this volume pair information, a replication creation request is transmitted to the other control units.

Abstract: For a storage system having plural control units to which plural disk devices are connected, in the method for creating replication in a volume of the disk devices connected to different control units, when receiving update I/O of a replication source during an initial copy for replication, the reflection of update to the replication destination is performed on an extension of the same I/O. When a pair is divided after the completion of copying, the update position is retained on the differential bitmap disposed in the individual control units, and the differential bitmap is merged to one of the control units at a time of resynchronization to perform copy processing.

Abstract: Information about remote copy target volumes of other storage systems 2 each having one and the same original volume V1 is registered for each remote copy target volume in advance. When there occurs a failure in a copy source storage system 2, a copy source volume for remote copy target volumes using the storage system 2 having a failure as their copy source is selected newly from the registered copy source volumes, and remote copy is resumed.

Abstract: A plurality of modules (1) and (2) comprise a plurality of virtual volumes with which the same volume identification number is associated. A module (2), which receives a write request from a computer, searches for an unallocated real area from among a plurality of real areas in the module (2) rather than from among a plurality of real areas in the other module (1) if a real area has not been allocated to a write-targeted virtual area in accordance with the write request. The module (2) allocates the real area retrieved from the module (2) to the write-targeted virtual area, and writes data according to the write request to this real area.

Abstract: A plurality of global LDEV managed by a plurality of controller modules are provided above local LDEV under the control of each controller module. Each global LDEV is correlated to any of the plurality of local LDEV. The controller modules judge whether or not a local LDEV correlated to a global LDEV specified by an I/O request received from a host device or a first other controller module is a management target itself, and if the result of that judgment is affirmative, the controller modules access the local LDEV correlated to the specified global LDEV, while if the result of the judgment is negative, the controller modules transfer the received I/O request to a second other controller module.

Abstract: When data in the first primary volume is migrated to the second primary volume, an access request from the host to the primary volume is transferred to the second primary volume. Further, the second storage system stores write data received from the host and data of the first primary volume received from the storage system, into the second primary volume. Out of data stored in the second primary volume, the second storage system sends data determined by management information received from the first storage system, to the third storage system.

Abstract: In a storage system having a plurality of control units each connected with a plurality of disk units, it is provided that a replication is created in the volume of the disk units connected to different control units. The replication creation unit of a given control unit creates a replication in the volume of the disk unit connected to other control units in such a manner that the original volume information, the replication volume information in the control unit and information on the other control units are registered as volume pair information. Based on this volume pair information, a replication creation request is transmitted to the other control units.