Abstract: A backup system having duplicated file system data and composed of a plurality of storage systems having different performances is provided, wherein a processing time required for backup of a small-sized file or an on-demand restoration of a file is reduced. A distributed backup system composed of a storage system and a plurality of backup units is equipped with a function for selecting a backup unit based on a plurality of performance indexes, and a requested data transfer size for performing backup or restoration is considered when performing the selection.

Abstract: Difference information between two snapshots from a first point-in-time snapshot, which has been copied, to an N.sup.th point-in-time snapshot, which constitutes the latest point-in-time snapshot, is acquired to a memory module. The memory module stores two or more pieces of difference information. The two or more pieces of difference information comprise difference information that shows the difference between a first point-in-time snapshot and any snapshot other than the first point-in-time snapshot of N snapshots. Copy difference information, which is information that shows the difference between the first point-in-time snapshot and a specified snapshot from among N snapshots, and which is used in copying the specified snapshot, is created on the basis of the two or more pieces of difference information.

Abstract: An aspect of this invention is a computer system, including: a storage apparatus for allocating real storage areas of a plurality of tiers of a tiered real storage area pool to a volume, and migrating and relocating data within the volume between the plurality of tiers; and a host apparatus that accesses the volume provided by the storage apparatus. The host apparatus is configured to refer to tier information including information on a corresponding one of the plurality of tiers to which an access destination address within the volume belongs to identify the corresponding one of the plurality of tiers to which the access destination address belongs and refer to settings predetermined for the plurality of tiers to perform I/O control for the access destination address based on settings of the identified corresponding one of the plurality of tiers.

Abstract: Difference information between two snapshots from a first point-in-time snapshot, which has been copied, to an N.sup.th point-in-time snapshot, which constitutes the latest point-in-time snapshot, is acquired to a memory module. The memory module stores two or more pieces of difference information. The two or more pieces of difference information comprise difference information that shows the difference between a first point-in-time snapshot and any snapshot other than the first point-in-time snapshot of N snapshots. Copy difference information, which is information that shows the difference between the first point-in-time snapshot and a specified snapshot from among N snapshots, and which is used in copying the specified snapshot, is created on the basis of the two or more pieces of difference information.

Abstract: Recently, along with the increase in the importance of data protection, there are increasing demands for constructing a computer system capable of protecting data even when widespread disaster occurs. In order to reduce the risk of data loss even when widespread disaster occurs, the present invention computes the risk of data loss for each replication relationship of data (combination of storage subsystems storing the same data), and allocates data so that the risks of losing data of all replication relationships are optimized.

Abstract: An electromagnetic flowmeter using a square wave excitation method includes a differential amplifier which outputs a detection signal; an analog-digital converter which converts the detection signal into a digital detection signal; a timing control circuit which generates a sampling signal for sampling the digital detection signal; an calculation unit which executes a flow rate calculation process and a abnormality judging process at a same time. The flow rate calculation process acquires a flow velocity output signal by sampling the digital detection signal in a flat portion in a positive/negative excitation section.

Abstract: Each time the file access request is received, it is discriminated whether there is an ACL which corresponds with the file system of the type following the switching in the file designated by the file access request. In cases where the judgment result is that there is no such ACL, an ACL which corresponds with the file system of the type following the switching is generated on the basis of an ACL which corresponds with the file system of the type prior to the switching which is associated with the designated file, and the ACL thus generated is used to control access in accordance with the received file access request.

Abstract: A method and a storage system are provided for implementing a sustained large block random write performance mechanism for shingled magnetic recording (SMR) drives in a redundant array of inexpensive disks (RAID). A Solid State Drive (SSD) is provided with the SMR drives in the RAID. The SSD is used in a hot spare mode, which is activated when a large block random-write event is identified for a SMR drive in the RAID. In the hot spare mode, the SSD temporarily receives new incoming writes for the identified SMR drive. Then the identified SMR drive is updated from the SSD to restore the state of the identified SMR drive, and operations continue with normal writing only using the SMR drives in the RAID.

Abstract: Erroneous deletion of data due to a collision of digest information during data de-duplication using digest information is prevented. When backup data is stored on a backup server 1100, digest information of the backup data is generated and stored in a digest information management table 4200. In addition, when a backup data storage request is made to the backup server 1100, a digest information verification control sub-program 1127 generates digest information of data to be backed up, and performs verification against the digest information of the backed up data already stored on the backup server 1100. If, by this verification, it is found that backed up data having the same digest information is already stored, de-duplication is realized by reusing the existing backed up data without newly storing the data to be backed up.

Abstract: In file de-duplication using hash value comparison, hash values of all target files must be calculated and actual data of all files must be read for hash value calculation, so that the processing time was long. The present invention provides a file storage system comprising a controller and a volume storing a plurality of files, the volume including a first directory storing a first file and a second file and a second directory storing a third file being created, wherein the controller migrates actual data of the second file to the third file, sets up a management information of the second file so that the third file is referred to when the second file is read, and if the sizes of actual data of the first file and the actual data of the third file are identical and the binaries of the actual data of the first file and the actual data of the third file are identical, sets up a management information of the first file to refer to the third file when reading the first file.

Abstract: Root node arrangements configured to carry out file level virtualization for logically providing a plurality of share units that can be shared among file systems of the root node or other one or more root nodes, to a client.

Abstract: A control unit of a storage system controller receives an access command to a first file specifying a first access position in the first file. A storage apparatus stores management information of the first file and management information of each of subfiles obtained by dividing the first file. The management information of the first file contains information associating a data position in the first file and management information of a subfile containning data at the data position. The management information of each of the subfiles contains information associating a data position in the corresponding subfile and a physical storage position. The control unit references the management information of the first file to identify the management information of the subfile containning the data at the first access position, and references the management information of the identified subfile to identify a physical storage position of the first access position.

Abstract: Proposed are a computer system and a data migration method which enable an improved response performance to a data access request from the user. A client computer or an application on a second file server transmits an access request for access to data stored in a first storage area to a second file server and, if an access request from the client computer is received, the second file server migrates data from a first storage area of a first storage apparatus to a second storage area of a second storage apparatus and, if an access request from the application on the second file server is received, data is migrated from the first storage area of the first storage apparatus to a third storage area of a third storage apparatus.

Abstract: The prior art information system could not migrate a file in a file sharing system provided by a file storage to a plurality of cloud storages having different forms of connection and different properties, and therefore, could not manage the files via a single Stub information. The present invention provides a data mover program in a file storage to select one or more migration destination cloud storages based on a migration policy, a connection information table of cloud storages and a property information table of cloud storages. Then, a Stub information of the migrated file is created, and an identification information of the file in the cloud storage is stored in a file information table. When access occurs from a client to a file storage, the data mover program downloads a file from the cloud storage stored in the file information table corresponding to the Stub information and provides the file to the client.

Abstract: In the prior art clone creating technique of a file, a management table of a snapshot and the file was created when creating the clone file, so that a considerable amount of creation time for creating the clone file and storage capacity was required. In order to solve the problems of the prior art, the present invention provides a system wherein if a request to create a clone of a file is received, a differential file is created while inhibiting update of the file, and update data is written to the differential file. Further, when a first update request is received to the differential file after creating the differential file, a management table is created. According to the invention, a large amount of clone files can be created speedily.

Abstract: A root node creates and issues an object ID comprising share information designating a share unit, which is a logical public unit. The share unit is a logical public unit comprising no less than two objects. Transfer control information in which share information is associated with device information showing a device for managing this share unit, is prepared for each share unit. The root node receives request data, which has an object ID comprising share information, specifies device information corresponding to the share information in this object ID from the transfer control information, and transfers the request data to the device indicated in this device information.

Abstract: A backup control apparatus which references duplication management information which includes first stored location information indicating the stored location of first information resource and second stored location information indicating the stored location of a second information resource which duplicates the first information resource, and identifies, from among a plurality of information resources belonging to a backup region. The first information resource stored in the location indicated by the first stored location information, and a second information resource stored in the location indicated by the second stored location information corresponding to the first stored location information. The backup control apparatus replaces the identified second information resource with linked information indicating a link to the identified first information resource, and backs up the backup region in which the second information resource is replaced with the linked information.

Abstract: A storage system 103 carries out first and second de-duplication processes in response to receiving a write request from a client. First, a determination is made as to whether a write target data item overlaps with any of the stored data items of a part of a stored data item group, which is a user data item group stored in a storage device 209, and if so, the write target data item is prevented from being stored in the storage device. Second, a determination is made as to whether a target stored data item, which is not finished being evaluated as to whether it overlaps with the stored data item in the first de-duplication process, overlaps with another stored data item, and if so, the target stored data item or the same data item overlapping with the target stored data item is deleted from the storage device 209.

Abstract: Difference information between two snapshots from a first point-in-time snapshot, which has been copied, to an N.sup.th point-in-time snapshot, which constitutes the latest point-in-time snapshot, is acquired to a memory module. The memory module stores two or more pieces of difference information. The two or more pieces of difference information comprise difference information that shows the difference between a first point-in-time snapshot and any snapshot other than the first point-in-time snapshot of N snapshots. Copy difference information, which is information that shows the difference between the first point-in-time snapshot and a specified snapshot from among N snapshots, and which is used in copying the specified snapshot, is created on the basis of the two or more pieces of difference information.

Abstract: To inhibit deterioration in the I/O performance of a file even if the file includes an area that is frequently accessed. An access account of the file is recorded, an area of the file is split into a plurality of partial areas at least one or more times if the access count exceeds a split threshold, the partial area (partial area including a hotspot with frequent access) in which the access count exceeded the split threshold is minimized, data corresponding to that partial area is ultimately uncompressed, and data corresponding to the other partial areas is compressed.