Abstract: Systems and methods are provided for automating a provision of applications from a source to a target by providing a virtual copy of application data, wherein the virtual copy can be adapted to a plurality of different target environments. Versions of source application data from an application database at a source production server are maintained at times associated with a schedule. Data associated with a request is received from a user to provision the source application data for a target environment at a target server, the request further comprising application specific parameters that define necessary requirements for the target environment. A virtual copy of the source application data is presented to the target server. Instructions to the target server are transmitted that define how to restore an operational server database from the virtual copy based on the application specific parameters to meet the requirements of the target environment.

Abstract: A method and system comprising splitting an IO in a system; intercepting the IO in an appliance; determining whether the IO is directed to a replicated file system; sending the IO directed to the replicated file system to a replication device; and acknowledging the receipt of the IO. A method, system and computer program product comprising requesting access to a point in time in a replicated file system; determining from a plurality of bookmarks of file system configurations; a bookmark corresponding to the point in time; determining if the current configuration of the file system is equivalent to the bookmark; and reconfiguring the file system when the current configuration is not equivalent to the configuration of the bookmark.

Abstract: A system for migrating a virtual machine includes: a first device; and a second device. The first device notifies the second device of failure information indicating that data transported to the second device includes an error originated from the first device, when the error is detected from a storage area in the first device. The second device writes a second identifier, whose value is different from that of a first identifier, into a memory of the second device while associating the second identifier with a second address, the second address being to serve as a copy destination of data indicated by the failure information, wherein the first identifier indicates that data in the second address includes an error originated from the second device, and the second identifier serves as an identifier indicating that data in the second address includes an error originated from the first device.

Abstract: Embodiments relating to garbage collection for a deduplicated and compressed storage device are described. One embodiment provides for a data storage system comprising an array of redundant storage devices including a first set of storage devices to be configured as live storage devices and a second set of storage devices to be configured as spare storage devices, a spare storage device to be enabled in event of a failure of a live storage device; and a set of processing devices coupled to the array of redundant storage devices, the set of processing devices to execute logic to enable data replication and deduplication for the array of redundant storage devices and perform distributed deduplication garbage collection on the first set of storage devices using one or more devices in the second set of storage devices as temporary storage.

Abstract: The present disclosure provides methods and systems for storing and accessing data in a distributed data storage system. The distributed data storage system includes a plurality of data storage nodes. The method includes receiving a data storing request. Then, a pseudo-random sequence of data storage nodes of the plurality of data storage nodes is generated, wherein the pseudo-random sequence is not sequential from any starting position and each data storage node of the pseudo-random sequence of data storage nodes is determined using a pre-determined pseudo-random function that is a function of a data reference. Finally, a data is stored into at least one data storage node of the pseudo-random sequence of data storage nodes based on a pre-defined selection criteria. The distributed data storage system includes an access server configured to store into and access data from at least one data storage node of data storage nodes.

Abstract: A method for execution by a dispersed storage and task (DST) processing unit includes generating storage unit performance data based on a performance threshold value and storage unit performance values of storage units in a storage unit write set. Storage unit write set data indicating a new storage unit write set based on the storage unit performance data is generated, where at least one slow-performing storage unit is removed from the storage unit write set to create the new storage unit write set when the at least one slow-performing storage unit has a storage unit performance value that compares unfavorably to the performance threshold value. A plurality of write requests are generated for transmission to the new storage unit write set via a network, each including a data slices to be written to a corresponding storage unit of the new storage unit write set.

Abstract: A facility for processing textual input generated with a user input device described. In one example facility, the facility stores the textual input in a first data structure contained in the address space of a first process. The facility synchronizes contents of the first data structure to a second data structure contained in the address space of a second process distinct from the first process, an application executing in the second process being configured to consume textual input synchronized to the second data structure.

Abstract: A data storage system has first and second computing nodes that are interconnected by a switchless fabric. Each storage node includes first and second paired storage directors with an interconnecting communication link. Atomic operations sent between the computing nodes are mediated by network adapters. Atomic operations sent between paired storage directors via the interconnecting communication link are provided to a network adapter via an internal port and mediated by network adapter. The interconnecting communication links can be used as a backup path for atomic operations in the event of a link failure of the switchless fabric.

Abstract: Large-scale data migration processes are managed using a schedule optimizer implemented in software. The schedule optimizer assigns an available data migration window to each server in an inventory of servers based on a scheduling priority determined for that server. For example, servers that have manually scheduled conversion dates are assigned the highest scheduling priority, and servers that have a migration deadline are assigned the next highest scheduling priority. In addition, servers may grouped and data migration may be scheduled for server groups instead of individual servers.

Abstract: A method for re-establishing a backup relationship between first and second volumes associated with one or more storage media in a data storage system is provided. The method comprises storing first information for preserving the backup relationship, in response to or in advance of receiving a request to terminate the backup relationship; recording changes to the first or second volumes that occur subsequent to terminating the backup relationship; and re-establishing the backup relationship between the first and second volumes according to the first information such that the first and second volumes are synchronized by merging the recorded changes with the first or second volumes.

Abstract: Techniques for adjusting the frequency of data backups and initiating event-driven backups in a storage system are disclosed herein. In one embodiment, a self-adjusting backup frequency, known as a “Change Rate Objective,” is defined to conduct or delay backups for one or more volumes in the storage system on the basis of an associated policy value. The Change Rate Objective may be tied to one or more business or data activity events, such as the amount and type of data changes since a last backup. The storage system may also be tailored to conduct or delay full or incremental backups on the basis of a Change Rate Objective that measures whether a full or incremental or differential backup is more appropriate. Various data or system failures, or data or business events may also be used to adjust the retention periods of continuous data protection (CDP) data and delay a rollup of CDP data.

Abstract: According to embodiments of the present invention, a metadata file is transferred from the first system to the second system and a database on the second system is initialized based on the metadata file. An image, including information of the first system to be restored, is transferred from the first system to the second system, and restoration of the information to the second system based on the image is initiated. Prior to completion of the restoration, one or more log files indicating actions performed on the first system relating to the information to be restored is transferred from the first system to the initialized database on the second system. In response to completion of the restoration, the actions of the log files are performed to synchronize the restored data on the second system with the first system.

Abstract: According to embodiments of the present invention, a metadata file is transferred from the first system to the second system and a database on the second system is initialized based on the metadata file. An image, including information of the first system to be restored, is transferred from the first system to the second system, and restoration of the information to the second system based on the image is initiated. Prior to completion of the restoration, one or more log files indicating actions performed on the first system relating to the information to be restored is transferred from the first system to the initialized database on the second system. In response to completion of the restoration, the actions of the log files are performed to synchronize the restored data on the second system with the first system.

Abstract: Performing failover processing between a production host and a backup host, a storage system is connected to the production host and the backup host. In response to a failure of the production host, metadata is obtained of data blocks that have been cached from an elastic space located in a fast disk of the storage system. A storage capacity of the elastic space is expanded. Data blocks are obtained to which the metadata corresponds according to the metadata and the storage capacity of the expanded elastic space, and storing the same in the expanded elastic space. In response the backup host requesting the data blocks to which the metadata corresponds, and the data blocks to which the metadata corresponds have already been stored in the expanded elastic space, data blocks are obtained to which the metadata corresponds from the expanded elastic space and transmitting the same to the backup host.

Abstract: A method for operating a mirrored disk storage system, comprises a determiner component for determining a repair characteristic of a pair of mirrored disks, a comparator for comparing said repair characteristic of a first of said pair with said repair characteristic of a second of said pair, and a cancelling component for cancelling a repair action for said one of said first or said second of said pair that is not selected by said selector.

Abstract: A mechanism is provided for optimizing migration/copying of de-duplicated data from an internal storage system to a removable storage system. A preliminary number of clusters to be generated are determined for sets of data objects stored on the internal storage system based on a number of the sets of data objects. The preliminary number of clusters is generated based on shortest distances between the sets of data objects, each cluster comprising one or more sets of data objects and each set of data objects comprising one or more chunks of data. A chosen cluster is identified from a set of clusters by identifying a cluster having a greatest number of common chunks within as few sets of data objects. Responsive to an export-size of the chosen cluster failing to exceed the available storage capacity of the removable storage system, the chosen cluster is exported to the removable storage system.

Abstract: A mechanism is provided for optimizing migration/copying of de-duplicated data from an internal storage system to a removable storage system. A preliminary number of clusters to be generated are determined for sets of data objects stored on the internal storage system based on a number of the sets of data objects. The preliminary number of clusters is generated based on shortest distances between the sets of data objects, each cluster comprising one or more sets of data objects and each set of data objects comprising one or more chunks of data. A chosen cluster is identified from a set of clusters by identifying a cluster having a greatest number of common chunks within as few sets of data objects. Responsive to an export-size of the chosen cluster failing to exceed the available storage capacity of the removable storage system, the chosen cluster is exported to the removable storage system.

Abstract: Examples described herein include a data migration system for migrating data between different data storage environments. The data migration system creates a first volume on a first storage system, and creates a logical unit within the first volume. The data migration system then creates a virtual volume on a virtual storage system associated with a second storage system, wherein data stored in the virtual volume is backed by the logical unit on the first storage system. The data migration system then replicates, on the virtual volume, a set of data stored on the second storage system. Upon replicating the set of data onto the virtual volume the virtual storage system may automatically create a copy of the corresponding data in the logical unit of the first volume.

Abstract: A storage migration engine and a recovery manager are provided that enable failover operations to be performed in situations where storage migration and array-based replication are involved. The storage migration engine stores information related to storage migrations directly into a source datastore and a destination datastore, which are then replicated over to a recovery site. The recovery manager uses the information stored in the recovered datastores to select which instance of virtual machine data is to be used to fail over to a virtual machine at the recovery site.

Abstract: A method for mirroring data between virtual machines includes intercepting a write command initiated from a virtual machine. Address and data information from the intercepted write command is stored within a queue located within a memory buffer of the primary server. The stored address and data information is transferred, upon filling the queue of the memory buffer of the primary server to a predetermined level, to a dedicated region of the memory of the primary server. The stored address and data information is sent from the dedicated region of the memory of the primary server to a backup server upon filling of the dedicated region of the memory of the primary server to a predetermined level.

Abstract: Techniques for synchronizing storage areas are disclosed. In one particular exemplary embodiment, the techniques may be realized as an apparatus for synchronizing storage areas comprising a module to identify one or more source storage areas associated with a virtual machine, a module to create one or more destination storage areas corresponding to the one or more source storage areas, a module to link the one or more source storage areas with the one or more destination storage areas, a module to synchronize the one or more source areas with the one or more destination areas, and when synchronization is complete, a module to associate the virtual machine with the one or more destination storage areas and disassociate the virtual machine with the one or more source storage areas.

Abstract: In one aspect of the present description, handling multiple backup processes comprises detecting that a defined storage volume is present in a first cascade of storage volumes; detecting that the defined storage volume is present in a second cascade of storage volumes; receiving a data write for a last storage volume in the first cascade of storage volumes; and performing a cleaning data write on the defined storage volume in the second cascade of storage volumes, wherein the cleaning data write corresponds to the received data write. Other aspects may be utilized, depending upon the particular application.

Abstract: An apparatus and method are described for performing partial memory mirroring operations. For example, one embodiment of a processor comprises: a processor core for generating a read or write transaction having a system memory address; a home agent identified to service the read or write transaction based on the system memory address; one or more target address decoders (TADs) associated with the home agent to determine whether the system memory address is within a mirrored memory region or a non-mirrored memory region, wherein: if the system memory address is within a mirrored memory region, then the one or more TADs identifying multiple mirrored memory channels for the read or write transaction; and if the system memory address is not within a mirrored memory region, then the one or more TADs identifying a single memory channel for the read or write transaction.

Abstract: A storage system includes a plurality of nodes connected to a network. Each node is capable of performing its own recovery of partially written data and maintaining consistency of the data stored on the storage system. The nodes may independently calculate the location of the data across the nodes and independently balance the data, maintain consistency based on a redundancy policy of the storage system, and migrate data according to a location change. If a node determines that the stored data thereon is incomplete or damaged, the node may reconstruct its respective data from replica data on other nodes. During migration of data between the nodes, I/O processing from a host is not interrupted in some examples.

Abstract: In a backup method, a first controller of a storage system receives a file process request, and divides the file process request into a plurality of file operations. The first controller processes each of the file operations to generate multiple pieces of file operation information. And then, the first controller writes all of the multiple pieces of file operation information into a cache protected area. When the first controller fails, it stores the multiple pieces of file operation information to a disk protected area of a disk in the storage system. After the first controller is powered on again, the first controller copies the multiple pieces of file operation information from the disk protected area to the cache protected area. And then, it writes the file operation information into a write cache. At last, the first controller stores the file operation information into a disk of the storage system.

Abstract: A storage system includes a plurality of nodes connected to a network. Each node is capable of performing its own recovery of partially written data and maintaining consistency of the data stored on the storage system. The nodes may independently calculate the location of the data across the nodes and independently balance the data, maintain consistency based on a redundancy policy of the storage system, and migrate data according to a location change. If a node determines that the stored data thereon is incomplete or damaged, the node may reconstruct its respective data from replica data on other nodes. During migration of data between the nodes, I/O processing from a host is not interrupted in some examples.

Abstract: A system includes a plurality of storage devices and an information processing device including a cache memory. The information processing device is configured to access the plurality of storage devices. When a failure has occurred in a first storage device included in the plurality of storage devices, the information processing device perform a procedure including: specifying a second storage device in which no failure has occurred, among the plurality of storage devices, creating an invisible file including a cache that has been stored in the cash memory and is to be stored in the first storage device, and storing the created invisible file in the second storage device. The information processing device stores the cache included in the invisible file stored in the second storage device, in the first storage device when the failure of the first storage device is eliminated.

Abstract: One embodiment is a system, comprising a first NAS device, a second NAS device. The first and second NAS devices may be configured to be paired with one another to enable an ongoing secure exchange of content (e.g., files, pictures, movies, audio recordings) and NAS settings (e.g., RAID settings, backup schedules, etc.) between the first and second NAS devices across a network. According to one embodiment, through this ongoing secure exchange of content and NAS settings, the second NAS device may become and may be thereafter maintained as a mirror of the first NAS device, such that the second NAS device may be maintained as a drop-in physical and functional replacement for the first NAS device in the event of a failure of the first NAS device.

Abstract: A storage control apparatus includes: a detector configured to detect a failure in one of a plurality of storages, each of a plurality of cabinets coupled in a cascade and having the plurality of storage units; a mover configured to move data in one or a plurality of first storages accommodated in a first cabinet including a failed storage having the failure detected by detector to one or a plurality of second storages accommodated in a second cabinet included in the plurality of cabinets; and a connection controller configured to control a first connection between the first cabinet and the plurality of cabinets other than the first cabinet and a second connection between the plurality of first storages in the first cabinet and the plurality of cabinets other than the first cabinet.

Abstract: The storage devices of a storage device set (e.g., a RAID array) may generate a nonvolatile representation of the configuration of the storage device set, including logical disks, spaces, storage pools, and layout and provisioning plans, on the physical media of the storage devices. A computer accessing the storage device set may also generate a volatile memory representation of the storage device set to use while accessing the storage devices; however, the nonvolatile representation may not be performant due to its different usage and characteristics. Presented herein are techniques for accessing the storage device set according to a volatile memory representation comprising a hierarchy of logical disks, slabs, and extents, and an accessory comprising a provisioning component that handles slab accesses while applying provisioning plans, and that interfaces with a lower-level layout component that translates slab accesses into storage device accesses while applying layout plans to the storage device set.

Abstract: A memory system is disclosed, which may include a memory unit of a first type, susceptible to loss of data from corrupting events, and a memory unit of a second type, less susceptible to loss of data from corrupting events than the memory unit of the first type, and a mirrored memory interface (MMI). The MMI may be coupled to a memory controller, the memory unit of the first type, and the memory unit of the second type. The MMI may, in response to a memory controller write command, receive data from the memory controller and write the data to the memory unit of the first type and to the memory unit of the second type. The MMI may also, in response to a memory controller read command, read data from the memory unit of the first type and send the data to the memory controller.

Abstract: A first SS (storage system) provides a first SA (storage area), a second SS provides a second SA, and first and second HSs (host systems) are coupled to the first and second SSs. First and second paths connect the first HS to the first and second SAs. Third and fourth paths connect the second HS to the first and second SAs. When the first path has a higher priority than the second path after recovery where a WR (write request) is permitted to be transmitted to the first SS, if the first SA which is a write destination for the received WR is a target in a data mirroring process, the first SS transmits a notification to stop the process. The second SS performs control such that a WR specifying the second SA as a write destination fails, and then the second HS transmits the WR using the third path.

Abstract: A method for optimizing cleaning of maps in storage cascades includes determining whether a target disk of a map contains data unavailable to a downstream disk from an upstream disk in a cascade and detect whether the downstream disk has a copy of the data. Additionally, the method includes copying the data from the target disk to the downstream disk, if the target disk of the map contains data unavailable to the downstream disk from the upstream disk and the downstream disk does not have the copy of the data. Furthermore, the method includes copying the data from the target disk to the downstream disk, if the target disk of the map does not contain data unavailable to the downstream disk from the upstream disk or the downstream disk does have the copy of the data. Moreover, the method includes removing the map from the cascade.

Abstract: A hibernation method of a computing system that includes generating backup data and write addresses according to at least a portion of data utilized by the computing system at a hibernation request, generating conversion addresses corresponding to a first non-volatile memory when the write addresses correspond to a second non-volatile memory, and storing the backup data in the first non-volatile memory according to either the write addresses or the conversion addresses.

Abstract: A method begins, as data objects are ingested, by determining, for each of some of the data objects, a priority indicator to produce a listing of priority indicators. The method continues for a data object by determining encoding parameters based on a corresponding priority indicator. The method continues by encoding the data object in accordance with the encoding parameters to produce a plurality of sets of encoded data slices and storing them. The method continues by identifying a first data object for analysis based on a corresponding priority indicator and an analysis priority. The method continues by decoding a plurality of sets of encoded data slices to recover the first data object and analyzing it in accordance with analysis criteria to determine its relevancy. The method continues by issuing a command to delete the plurality of sets of encoded data slices when the relevancy is below a threshold.

Abstract: A method for managing data swapping in a migration of virtual memory data in a virtual machine, where the data swapping is from a first host associated with a first storage device to a second host associated with a second storage device, is provided in another embodiment. The method includes receiving a migration instruction indicating the virtual machine to be migrated, and instructing the first host to copy data of the virtual machine to a sub-logical unit in the first storage device, the sub-logical unit having a mirror logical unit in the second storage device. A notification is sent, the notification being usable to instruct the second host to read data from the mirror logical unit.

Abstract: A storage control device includes a storage unit and a processor. The storage unit is configured to store therein a first score calculated for a first storage device. The processor is configured to add, upon detecting an event occurred in the first storage device, points corresponding to the event to the first score. The processor is configured to determine upon the addition, based on the first score and a second score, whether a sign of failure of the first storage device is detected. The second score is calculated for a first redundant unit of storage devices including the first storage device.

Abstract: According to one embodiment, there is provided a memory system including a first storage medium group, a second storage medium group, and a controller. The controller is configured to multiply write the same data to the first storage medium group and the second storage medium group. And the controller is configured to transmit data read out from a storage medium group selected from the first storage medium group and the second storage medium group to a host according to a progress status of a readout process for the first storage medium group and the second storage medium group when receiving a readout command of stored data in the first storage medium group and the second storage medium group from the host.

Abstract: An information processing method in embodiments of this invention includes: detecting a failure sign of a first physical disk in a system having plural physical disks, each of which stores one or plural virtual disks included in a virtual machine that is executed on a physical machine; identifying one or plural certain virtual disks stored in the first physical disk; and moving at least one of the identified one or plural certain virtual disks to a second physical disk that is a physical disk other than the first physical disk and has a capability to store a virtual disk to be moved to the second physical disk, based on a dynamic or static characteristic of the one or plural certain virtual disks or a dynamic or static characteristic of a physical disk other than the first physical disk.

Abstract: According to this invention, a highly reliable memory device that uses up a life of a flash memory can be provided. The memory device is a nonvolatile memory device including a plurality of memory cells, in which: each of the plurality of memory cells is an FET which includes a floating gate; the plurality of memory cells are divided into a plurality of deletion blocks; and the nonvolatile memory device reads data stored in a first deletion block, detects and corrects an error contained in the read data, stores, when the number of bits of the detected error exceeds a threshold, the corrected data in a second deletion block, sets a smaller value as the threshold as an error frequency detected in the first deletion block is higher, and sets a smaller value as the threshold as the number of deletion times executed in the first deletion block is larger.

Abstract: A system and method for power management of storage resources are disclosed. A method may include detecting an occurrence of an event associated with a storage resource disposed in an array of storage resources. The method may further include transitioning the storage resource into a specified power state in response to the detection of the occurrence of the event. A system may include a storage resource and a power management module communicatively coupled to the storage resource. The storage resource may be disposed in an array of storage resources. The power management module may be operable to detect an occurrence of an event associated with the storage resource, and may be operable to transition the storage resource into a specified power state in response to the detection of the occurrence of the event.

Abstract: Handling failure of a primary group at a first data center that is part of plurality of data centers providing triangular asynchronous replication, includes creating a data mirroring relationship between at least one storage volume at a second data center having a synchronous backup group that is part of the plurality of data centers and at least one storage volume at a third data center having an asynchronous backup group that is part of the plurality of data centers and resuming work at the second data center. Handling failure of a primary group at a first data center may also include synchronizing the at least one storage volume at the second data center with the at least one storage volume at the third data center prior to resuming work at the second data center.

Abstract: A method of performing a data write on a storage device comprises instructing a device driver for the device to perform a write to the storage device, registering the device driver as a transaction participant with a transaction co-ordinator, executing a flashcopy of the storage device, performing the write on the storage device, and performing a two-phase commit between device driver and transaction co-ordinator. Preferably, the method comprises receiving an instruction to perform a rollback, and reversing the data write according to the flashcopy. In a further refinement, a method of scheduling a flashcopy of a storage device comprises receiving an instruction to perform a flashcopy, ascertaining the current transaction in relation to the device, registering the device driver for the device as a transaction participant in the current transaction with a transaction co-ordinator, receiving a transaction complete indication from the co-ordinator, and executing the flashcopy for the device.

Abstract: A storage system including a first boot drive configured to store an operating system, one or more data drives configured to store user data, the one or more data drives distinct from the first boot drive, and a controller configured to detect when a second boot drive is added to the storage system, and automatically configure the first boot drive and the second boot drive in a redundant array of independent disks (“RAID”) configuration when the controller detects that the second boot drive is added to the storage system.

Abstract: A mechanism is provided in a data processing system. The mechanism determines a maximum queue depth of a queue for each solid state drive in a plurality of solid state drives. A given data block is mirrored between a group of solid state drives within the plurality of solid state drives. The mechanism tracks outstanding input/output operations in a queue for each of the plurality of solid state drives. For a given read operation to read the given data block, the mechanism identifies a solid state drive within the group of solid state drives based on a number of empty slots in the queue of each solid state drive within the group of solid state drives.

Abstract: A system, method, and computer program product for intercepting Input/Outputs (IOs) sent to a second storage medium in a storage array via a splitter in the storage array, redirecting read IOs to a first storage medium, and redirecting writes to the first storage medium and a Data Protection appliance.

Abstract: A method of replicating tiered data includes copying a volume from a first tiered storage array of a primary processing site to a second tiered storage array of a failover processing site, wherein the volume is tiered with a first tiered organization in both the first and second tiered storage arrays, directing from a first storage controller of the primary processing site that a second storage controller of the failover processing site stop tiering the volume on the second tiered storage array, changing the first tiered organization of the volume in the first tiered storage array to a second tiered organization, and changing the first tiered organization of the volume in the second tiered storage array to the second tiered organization.

Abstract: Since the whole storage device is blocked according to the conventional data saving method when failure occurs to the storage device in a storage subsystem, so that when failure occurs to two storage devices at the same time within a same RAID group, double failure is caused and data loss occurs. In order to solve the problem, the present invention divides a storage device into storage areas of predetermined units, constructs RAID groups from two or more storage areas, and when failure occurs to the storage area, selects a data migration destination storage area from either the RAID group in which failure has occurred or the RAID group other than the RAID group in which failure has occurred, migrates the data stored in the storage area where failure has occurred to the selected data migration destination storage area, and blocks only the storage area where failure has occurred.

Abstract: A method, computer program product, and computing system for storing an unsecure data portion within a temporary storage device. An indication of a power failure event within the storage system is received. The unsecure data portion is processed to produce a secure data portion via a processor included within a first controller card included within the storage system. The secure data portion is stored on a persistent storage device via a second controller card.

Abstract: A control device controls the switch device and the plurality of processing apparatuses such that, when one of replicated data pieces stored in two or more different storage devices among the plurality of storage devices is lost, the replicated data piece stored in a second storage device other than a first storage device storing lost replicated data piece among the two or more different storage devices is copied through the switch device to reconstruct the lost replicated data piece. Thus, a redundancy of replicated data is restored without affecting a bandwidth of a network.