Abstract: A virtualization system, upon judging that a write operation from a higher-level device is an operation to write in the format of the virtual volume, even when the write position of the write operation is in a virtual area different from a virtual area to which an allocated actual area has been allocated, if there is an unused area in the allocated actual area, writes management information to the unused area according to the write operation, and if there is no unused area in the allocated actual area, newly allocates an unallocated actual area, and writes management information to the newly allocated actual area according to the write operation.

Abstract: A virtualization system, upon judging that a write operation from a higher-level device is an operation to write in the format of the virtual volume, even when the write position of the write operation is in a virtual area different from a virtual area to which an allocated actual area has been allocated, if there is an unused area in the allocated actual area, writes management information to the unused area according to the write operation, and if there is no unused area in the allocated actual area, newly allocates an unallocated actual area, and writes management information to the newly allocated actual area according to the write operation.

Abstract: A storage control technique with which, even if not data, but only its management information is deleted, a host system can recognize storage areas storing unnecessary data and so use them effectively. When a file system in the host system deletes the management information for data stored in a page in a pool volume, a control circuit writes ‘0’ in all the areas in the deletion target page in response to a command from the host system. The control circuit then detects the page where ‘0’ is written in all of its areas and releases it from allocation to the corresponding virtual volume.

Abstract: A storage controller of the present invention detects error with relative ease when reading out data from a storage apparatus. An address data appending device appends address data to each of logical blocks with respect to the data received from a host. A device communication control device determines a divisional position in every data with a size of a predetermined number of blocks, counterchanges the data in anterior and posterior parts around the divisional position, and stores the data in the storage apparatus. When reading the data from the storage apparatus, an address data checking device determines whether or not the value of the address data appended to the block read out and an expected value of the address data calculated based on the divisional position match with each other. If the both values match with each other, the data is sent to the cache memory. If the both values fail to match each other, an error is detected.

Abstract: A storage control technique with which, even if not data, but only its management information is deleted, a host system can recognize storage areas storing unnecessary data and so use them effectively. When a file system in the host system deletes the management information for data stored in a page in a pool volume, a control circuit writes ‘0’ in all the areas in the deletion target page in response to a command from the host system. The control circuit then detects the page where ‘0’ is written in all of its areas and releases it from allocation to the corresponding virtual volume.

Abstract: The expansion of a mapping table with additional mapping information involved in the access to virtual volumes is prevented and so a search in the mapping information within a valid time period is ensured, thereby preventing degradation of system performance. A storage apparatus, which defines virtual volumes to which storage areas are dynamically allocated, has a data migration function to migrate data between the virtual volumes and real volumes. With the data migration function, the mapping information for the migrated data is deleted from the mapping table, and accordingly, the size of the mapping table can be limited.

Abstract: A storage controller of the present invention can input and output data even when the track size, which is the host management unit, is not consistent with the block size of the storage device. A boundary correction unit adds gap data corresponding to a gap size to data in a buffer memory so that the boundary of the track and boundary of the block inside the storage device match. A guarantee code is added to each logical block received from the host, and these guarantee code-appended blocks are stored in a cache memory. By providing a gap in the storage device every 116 extended logical blocks, the start position of the lead block of a track matches up with the start position of the logical blocks of the storage device.

Abstract: The present invention efficiently recovers an error drive by suppressing futile copying. When the number of errors of the disk drive is equal to or more than a first threshold, data stored in the disk drive is copied to a spare drive by a drive copy section. When the number of errors of the disk drive is equal to or more than a second threshold prior to completion of the drive copy, the disk drive is closed, and a correction copy by a correction copy section is started in place of the drive copy. The correction copy section starts the correction copy from the position where the drive copy is interrupted by taking over the drive copy completion position (copy interrupt position) managed by a copy progress condition management section.

Abstract: This storage apparatus for providing a dynamically expandable virtual volume to a host system to access the virtual volume comprises an allocation unit for configuring a group with a plurality of disks for providing a storage area to be allocated to the virtual volume, and allocating the storage area respectively from a plurality of the groups to the virtual volume; and a storage area arrangement unit for rearranging the storage area in each of the groups being used by the virtual volume to become optimal among each of the groups based on external operation.

Abstract: A storage system enabling effective use of storage resources by immediately releasing a storage device provided as a spare from data recovery processing for a faulty storage device. Even before the completion of the collection copy, the faulty disk drive may be replaced with a new disk drive and a relevant control unit in the storage system recognizes this replacement and has data in the spare disk drive automatically copied back to the new disk drive.

Abstract: A storage control technique with which, even if not data, but only its management information is deleted, a host system can recognize storage areas storing unnecessary data and so use them effectively. When a file system in the host system deletes the management information for data stored in a page in a pool volume, a control circuit writes ‘0’ in all the areas in the deletion target page in response to a command from the host system. The control circuit then detects the page where ‘0’ is written in all of its areas and releases it from allocation to the corresponding virtual volume.

Abstract: The expansion of a mapping table with additional mapping information involved in the access to virtual volumes is prevented and so a search in the mapping information within a valid time period is ensured, thereby preventing degradation of system performance. A storage apparatus, which defines virtual volumes to which storage areas are dynamically allocated, has a data migration function to migrate data between the virtual volumes and real volumes. With the data migration function, the mapping information for the migrated data is deleted from the mapping table, and accordingly, the size of the mapping table can be limited.

Abstract: The present invention allows the processing mode for write access operations to be set independently and respectively for prescribed units. The processing modes for handling write access are set previously for each of the volumes 6A and 6B. If the cache memory is functioning normally, write access operations to the respective volumes 6A and 6B are processed by means of an after-write method as illustrated in FIG. 1(a). If an abnormality has occurred in the cache memory, then write access operations to the volumes 6A and 6B are processed by means of a method previously selected from a write-through method as illustrated in FIG. 1(b) or a non-redundant storage type write-after method as illustrated in FIG. 1(c). By using different processing modes for write access, for each of the volumes 6A and 6B, it is possible to set a suitable processing mode respectively for each of the prescribed units, in accordance with the composition of the storage system, the operation configuration, and the like.

Abstract: A virtualization system, upon judging that a write operation from a higher-level device is an operation to write in the format of the virtual volume, even when the write position of the write operation is in a virtual area different from a virtual area to which an allocated actual area has been allocated, if there is an unused area in the allocated actual area, writes management information to the unused area according to the write operation, and if there is no unused area in the allocated actual area, newly allocates an unallocated actual area, and writes management information to the newly allocated actual area according to the write operation.

Abstract: During recovery of a master system, a mismatch between data in the master system and that in a backup system is obviated quickly to shorten time consumed before resumption of operation of the master system. The backup system controls, as second difference information, update data generated over a substitute operation period between occurrence of a disabled state of the master system and recovery thereof and when the master system is enabled to operate, a range of addition of first difference information inside the master system and the second difference information or only a range of the second difference information is copied to the master system to eliminate the data mismatch.

Abstract: The present invention efficiently recovers an error drive by suppressing futile copying. When the number of errors of the disk drive is equal to or more than a first threshold, data stored in the disk drive is copied to a spare drive by a drive copy section. When the number of errors of the disk drive is equal to or more than a second threshold prior to completion of the drive copy, the disk drive is closed, and a correction copy by a correction copy section is started in place of the drive copy. The correction copy section starts the correction copy from the position where the drive copy is interrupted by taking over the drive copy completion position (copy interrupt position) managed by a copy progress condition management section.

Abstract: Writing in each sector of a series of sectors of a recording medium in which data is to be written caused by a single data write request location information which is information indicating a location of the sector in the series of sectors and common information which varies every time data writing to the series of sectors occurs and is information set relating to the series of sectors.

Abstract: A storage system enabling effective use of storage resources by immediately releasing a storage device provided as a spare from data recovery processing for a faulty storage device. Even before the completion of the collection copy, the faulty disk drive may be replaced with a new disk drive and a relevant control unit in the storage system recognizes this replacement and has data in the spare disk drive automatically copied back to the new disk drive.

Abstract: The invention is intended to reduce disk access during data transfer from a disk in which occurrence of failure is anticipated to a spare disk as much as possible so that occurrence of double-failure is prevented in advance. When occurrence of failure in a disk which configures a RAID group, contents stored in the disk is copied to the spared disk. Simultaneously, another RAID group is paired with the above described RAID group and a secondary volume is provided therein. A write request is directed to the secondary volume. A differential bitmap controls a update data. Data which is not updated is read out from the primary volume, and data which is already updated is read from the secondary volume. When data transfer is completed, contents stored in the secondary volume are copied to the primary volume.

Abstract: The present invention allows the processing mode for write access operations to be set independently and respectively for prescribed units. The processing modes for handling write access are set previously for each of the volumes 6A and 6B. If the cache memory is functioning normally, write access operations to the respective volumes 6A and 6B are processed by means of an after-write method as illustrated in FIG. 1(a). If an abnormality has occurred in the cache memory, then write access operations to the volumes 6A and 6B are processed by means of a method previously selected from a write-through method as illustrated in FIG. 1(b) or a non-redundant storage type write-after method as illustrated in FIG. 1(c). By using different processing modes for write access, for each of the volumes 6A and 6B, it is possible to set a suitable processing mode respectively for each of the prescribed units, in accordance with the composition of the storage system, the operation configuration, and the like.