Abstract: A method of providing end-to-end encryption for data stored in a storage system, including: receiving a request to read encrypted data from a logical volume of a storage system; decrypting the encrypted data using a decryption key associated with at least one property of the storage system; performing at least one of a data operation to reconstitute the data; encrypting the data using an encryption key associated with at least one property of the data to generate new encrypted data; and providing a response to the request that includes the new encrypted data.

Abstract: A recovery solution can employ virtualization software to create a virtualized Active Directory forest from a source Active Directory forest. A recovery agent can be installed on the domain controllers prior to creating copies of the domain controllers in the virtualized forest. Additionally, the recovery agent can be added to a list of trusted applications if the domain controller includes security software. The recovery solution can employ the virtualization software to store a command file at a known directory path. This command file can include commands that should be executed on the virtualized domain controller to configure it properly. The recovery agent can be configured to periodically scan the known directory path to determine whether a command file has been stored in the directory. If the recovery agent locates a command file, it can extract and execute any commands in the command file.

Abstract: A system for a storage controller configuration system of a storage server comprises an input interface and a storage controller request creator. The input interface is for receiving one or more commands to instantiate a set of virtual storage devices. The storage controller request creator for: 1) providing instantiation instructions for the set of virtual storage devices for storage in a cache and 2) in the event a request is received to create a mapping between a virtual storage device of the set of storage devices, a LUN, a port, and a client initiator: providing an instantiation indication to instantiate the set of virtual storage devices and providing a storing indication to store the mapping in a LUN table.

Abstract: A system for executing a plurality of transactions comprises a first processor and a memory. The first processor is configured to execute a first transaction comprising: providing a plurality of indications to make a plurality of first changes to a plurality of first records of a database; and committing the first transaction by updating the status of the first transaction in a transaction table while not providing an indication to update the status of the first records from pending. The memory is coupled to the first processor and configured to store the transaction table.

Abstract: One or more techniques and/or computing devices are provided for secure data replication. For example, a first storage controller may host first storage within which storage resources (e.g., files, logical unit numbers (LUNs), volumes, etc.) are stored. The first storage controller may establish an access policy with a001 second storage controller to which data is to be replicated from the first storage. The access policy may define an authentication mechanism for the first storage controller to authenticate the second storage controller, an authorization mechanism specifying a type of access that the second storage controller has for a storage resource, and an access control mechanism specifying how the second storage controller's access to data of the storage resource is to be controlled. In this way, data replication requests may be authenticated and authorized so that data may be provided, according to the access control mechanism, in a secure manner.

Abstract: Methods, computer program products, and systems are presented. The methods include, for instance: enabling a client of a source site protected by a disaster recovery service, to select one or more value-added service to be performed by a data protection service provider in addition to the disaster recovery service. Respective dataset associated with a service is identified and analyzed to minimize the amount of dataset to replicate from the source site to a target site run by the data protection service provider, and a policy dictating when and how to replicate which dataset is configured. Upon being triggered, the data protection service provider performs the service by use of the dataset at the target site, the dataset either replicated according to the policy from the source site or being reconstructed from the transferred dataset when necessary.

Abstract: A method, article of manufacture, and apparatus for restoring data. In some embodiments, this includes determining an object to be recovered, determining a representation of the object, and requesting the representation of the object from a data resource system. In some embodiments, the representation of the object is a hash value of the object. In some embodiments, the representation of the object is a segment of the object.

Abstract: A system and method for data storage by shredding and deshredding of the data allows for various combinations of processing of the data to provide various resultant storage of the data. Data storage and retrieval functions include various combinations of data redundancy generation, data compression and decompression, data encryption and decryption, and data integrity by signature generation and verification. Data shredding is performed by shredders and data deshredding is performed by deshredders that have some implementations that allocate processing internally in the shredder and deshredder either in parallel to multiple processors or sequentially to a single processor. Other implementations use multiple processing through multi-level shredders and deshredders. Redundancy generation includes implementations using non-systematic encoding, systematic encoding, or a hybrid combination.

Abstract: Techniques for maintaining a cascading index are provided. In one approach, one or more branch node compression techniques are applied to the main index of a cascading index. In an approach, a Bloom filter is generated and associated with, e.g., a branch node in the main index. The Bloom filter is used to determine whether, without accessing any leaf blocks, a particular key value exists, e.g., in leaf blocks associated with the branch node. In an approach, a new redo record is generated in response to a merge operation between two levels of the cascading index. The new redo record comprises (a) one or more addresses of blocks that are affected by the merge operation, (b) data is that being “pushed down” to a lower level of the cascading index, and (c) one or more addresses of blocks that are written to storage as a result of the merge operation.

Abstract: Aspects of the present invention are directed to a system for next day reconciliation of transportation records. The system having a transportation record storage provider (TRSP) that receives and stores storage medium transportation requests; an outside service provider (OSP) inventory manager that receives and maintains records of transported storage mediums scanned at the OSP; and a reconciliation provider that receives a first list from the TRSP and a second list from the OSP inventory manger, for reconciliation. The reconciliation provider includes receivers for receiving the first and second list; a processing engine that reconciles the first list and the second list; and a reporting unit that reports the results of the reconciliation. The processing engine matches inbound and outbound records of the first list and second list, and processes invalid records; and analyzes and accounts for un-matched records.

Abstract: According to embodiments described herein, a backup server maintains backup data for a set of data, which includes data for a first block and a second block. Backup data for the first and second block include backup data for a plurality of versions of the first and second block. A distinct watermark is stored for each version of the first block and each version of the second block. In response to a request to perform a restoration operation on the set of data, a particular version of the first block and a particular version of the second block are selected to use in the restoration operation by comparing a restoration target with the watermarks of the version of the first block and second block. The selected version of the first block has a different watermark than the selected version of the second block.

Abstract: Techniques for accelerating data movement from a source storage system to a target storage system are described herein. According to one embodiment, a first data stream is received to be transmitted to a remote storage system over a network, the first data stream having multiple data objects, each identified by a data object identifier (ID). A difference is determined between the first data stream and a second data stream that has been previously transmitted to the remote storage system, including identifying one or more data objects that are added, deleted, and/or modified. Differential object information is transmitted to the target storage representing the difference between the first data stream and the second data stream, as well as one or more data objects that are missing in the second data stream without having to transmit all data objects of the first data stream.

Abstract: A cluster network environment may comprise a plurality of nodes configured to perform various tasks, such as data I/O, storage, backup, etc. It may be advantageous to improve disaster recovery and reliability by creating backups that may be used to restore the cluster network environment and/or nodes therein. Accordingly, one or more techniques and/or systems are disclosed for restoring a cluster network environment and/or nodes therein. In particular, cluster configuration data, which may be stored in a healthy node or at a remote source, may be used to restore a node affected by an integrity loss. If the integrity loss affects the cluster network environment (e.g., a majority of healthy nodes are lost), then a new cluster network environment may be created from a healthy node or a restored healthy node. The creation of the new cluster network environment may be based at least in part on cluster configuration data.

Abstract: Provided is a home appliance storage virtualization apparatus including a recognizer to recognize a plurality of home appliances that is disposed in a home network and includes storages, a file system to manage the storages of the plurality of home appliances as a single storage space, and a storage manager to control the plurality of home appliances to access the single storage space using the file system.

Abstract: Techniques to modify file descriptors for content files are described. An apparatus may comprise a processor circuit and a file descriptor application operative on the processor circuit to manage file descriptors for content files, the file descriptor application arranged to generate a file descriptor for a content file in accordance with a universal file descriptor model, the universal file descriptor model to comprise a file descriptor surface with multiple file descriptor tiles to present corresponding content parts from the content file, with at least one of the file descriptor tiles defining a content part class representing homogeneous content parts from heterogeneous content file types. The file descriptor application may also comprise a file descriptor editor component arranged to allow modifications to the file descriptor. Other embodiments are described and claimed.

Abstract: In an exemplary embodiment of this disclosure, a method for loading data from a backup image of a database includes selecting a subset statement defining a subset of the data in the database. Tables of the database are identified based on metadata of the database. A target database is written having the structure but not the data of the identified tables. One or more table statements are constructed, by a computer processor, defining a subset of each identified table based on the subset statement. Selected data is unloaded from a backup image into the target database using respective table statements as filters.

Abstract: Systems and methods are disclosed for recovering data following a directory service malfunction, such as a forest-wide disaster in Microsoft® Active Directory. In certain examples, a single management console can be used for remotely recovering selected domain controllers in the forest without necessitating direct operator intervention. Multiple domain controllers can be concurrently restored from one or more backup files. Configurations of the system can advantageously eliminate manual intervention with each domain controller, thereby saving significant amounts of recovery time and effort. Also, certain systems and methods can be used to automatically and remotely quarantine corrupt domain controllers so that those individual domain controllers do not replicate with the newly restored environment, while allowing the domain controllers to remain online and in communication with the attached network.

Abstract: Provided is a method for transferring multimedia content from the first device to a second device. The method includes scanning a memory associated with the second device to identify transcoding parameters associated and stored therein. The method also includes transcoding the multimedia content from the first device based upon the identified transcoding parameters.

Abstract: Aspects of the present invention are directed to a system for next day reconciliation of transportation records. The system having a transportation record storage provider (TRSP) that receives and stores storage medium transportation requests; an outside service provider (OSP) inventory manager that receives and maintains records of transported storage mediums scanned at the OSP; and a reconciliation provider that receives a first list from the TRSP and a second list from the OSP inventory manger, for reconciliation. The reconciliation provider includes receivers for receiving the first and second list; a processing engine that reconciles the first list and the second list; and a reporting unit that reports the results of the reconciliation. The processing engine matches inbound and outbound records of the first list and second list, and processes invalid records; and analyzes and accounts for un-matched records.

Abstract: A computer-implemented method for restoring multi-tier applications may include (1) identifying a request to restore a multi-tier application from a backup of the multi-tier application, the multi-tier application including a plurality of individually relocatable components, (2) in response to the request, retrieving a configuration data store from the backup, the configuration data store including a topology of the plurality of individually relocatable components, (3) parsing the configuration data store to extract at least a portion of the topology from the configuration data store, and (4) restoring at least a portion of the multi-tier application based on the portion of the topology. Various other methods, systems, and computer-readable media are also disclosed.

Abstract: Determinations are made regarding which database components are installed with a database installation. A recovery manual generator accesses system recovery data to generate a system recovery manual based on the system recovery data. A database feature auditor determines, based in part on the system recovery data, which database features are installed at database installations, which may be at multiple database sites.

Abstract: A computer system with read/write access to storage devices creates a snapshot of a data volume at a point in time while continuing to accept access requests to the mirrored data volume by copying before making changes to the base data volume. Multiple snapshots may be made of the same data volume at different points in time. Only data that is not stored in a previous snapshot volume or in the base data volume are stored in the most recent snapshot volume.

Abstract: Calendar repair using a standard message may be provided. Calendar events, such as appointments and meetings, may be created and copied to a plurality of attendee calendars. A first copy of the event may be compared to a second copy of the event to determine whether properties between the events are out-of-sync. If so, a standard meeting request message comprising the correct value may be sent to update the out-of-sync property.

Abstract: Disclosed are an apparatus, a system, and a method for recovering meta data using fragmentary information. The system for recovering meta data includes: a data server storing recovery information for recovering at least one data file and meta data related to each of the data file; and a meta data server storing the meta data related to the data files and receiving the recovery information from the data server when the meta data are lost to recover the lost meta data. By this configuration, the exemplary embodiment of the present invention stably can the lost meta data of the meta data server by using the recovery the meta data and prevent the phenomenon that the meta data collides with each other on the same directory hierarchical structure.

Abstract: A method is disclosed for reliably updating a data group in a read-before-write data replication environment. The method reliably updates the data group by receiving an updated data group sent from a first storage medium to a second storage medium, comparing the updated data group with a previous data group previously existing on the second storage medium and writing the updated data group to the second storage medium. The read-before-write and differencing method disclosed maintain reliability by storing multiple copies of changes made to the second storage medium during and after the write process.

Abstract: In one embodiment, a service mediator provides a service that is a composite of atomic services and executes a recovery pattern in the event that a service is not available. More particularly, in an initial phase of operation, the service mediator determines one or more recovery patterns for each atomic service offered in the composite service and stores in a database an identity of each such recovery pattern for each atomic service. In subsequent operation, the service mediator monitors the availability of each atomic service. When a user inquires of a composite service, the service mediator determines if any of its atomic services is unavailable. If an atomic service is unavailable, the service mediator selects a recovery pattern and executes it.

Abstract: A method of recovering information missing from a virtual file system is implemented at a computing device that is communicatively connected to one or more storage devices. Upon receipt of a request for a file associated with an instance of the virtual file system, the computing device retrieves a set of blocks associated with the file from one of the storage devices and identifies one or more of the set of blocks as missing blocks after failing to retrieve the missing blocks from the storage devices. For each missing block, the computing device retrieves one or more parity blocks from one of the storage devices and computes the missing block by applying a predefined recovery scheme to the retrieved parity blocks. Finally, the computing device reconstructs the requested file using the computed missing blocks and other blocks associated with the requested file.

Abstract: A business process catalog is built using pattern analysis of historical data of a database and deploying the built business process catalog to perform database recovery, A first set of statements are logged for transactions of a first business process batch and compared with a second set of statements. The second set of statements is included in a second business batch process stored in the business process catalog. The business process catalog is updated based on the comparison of the first and second sets of statements. The built business process catalog is deployed to identify and present business process batches to a database system user to select a business process batch used to perform the database system recovery.

Abstract: Recovering from a failure of a soon-to-fail database system among a plurality of database systems in a multi-database system in processing a request submitted to the multi-database system through a multi-database system session is accomplished. A query band is created for the request. The query band is defined to be an identifier that uniquely identifies the session and the request among the plurality of sessions and plurality of requests being processed by the multi-database system at the time that the request was submitted. The query band is attached to a transaction issued by the multi-database system to the soon-to-fail database system to execute the query. The status concerning execution of the transaction is reported by the soon-to-fail database system. The status includes the query band. The status is logged. The failure of the soon-to-fail database system is detected.

Abstract: An “operate with missing region” feature of this disclosure allows the cluster to continue servicing reads for available regions even when some regions are missing. In particular, upon a given node failure condition, the cluster is placed in an effective read-only mode for all regions. The node failure condition typically is one where there has been a failure of an authoritative region copy and no backup copy is then available. As used herein, “read-only” means that no client write or update requests will succeed while the cluster is in this state. In particular, those requests should fail with an error message (or the like) that indicates failure because of the read-only status. Preferably, such requests are then re-tried. In this mode, all regions are only allowed to perform read operations. During the read-only state, the cluster continues to operate with missing regions, and missing regions are entered on the region map.

Abstract: A method and system for identifying and tracing copies of a file is disclosed herein. The method/system includes assigning a unique serial number to each of the copies of the file; and designating a barcode corresponding to the unique serial number. The method/system requires identification of a purchaser of a given copy to be linked with the barcode, so that it can reference the association relations between the serial number and barcode to determine the identity of the purchaser.

Abstract: A system (and a method) is disclosed for fingerprinting based entity extraction using a rolling hash technique. The system is configured to receive an input stream comprising characters, the input stream of a predetermined length, and a hash table having plurality of indexed entries. The system defines a fixed window length. The system isolates, through the fixed window length, a set of a plurality of characters of the input stream. The system generates a hash key. The hash key is used to index into the hash table. The system compares the isolated set of plurality of characters of the input stream with the entry corresponding to the index into the hash table to determine whether there is an exact match with the entry. The system slides the fixed window length one character to isolate another set of a plurality of characters of the input stream in response to no exact match from the comparison. Alternatively, the system stores the input stream in response to an exact match from the comparison.

Abstract: A cluster network environment may comprise a plurality of nodes configured to perform various tasks, such as data I/O, storage, backup, etc. It may be advantageous to improve disaster recovery and reliability by creating backups that may be used to restore the cluster network environment and/or nodes therein. Accordingly, one or more techniques and/or systems are disclosed for restoring a cluster network environment and/or nodes therein. In particular, cluster configuration data, which may be stored in a healthy node or at a remote source, may be used to restore a node affected by an integrity loss. If the integrity loss affects the cluster network environment (e.g., a majority of healthy nodes are lost), then a new cluster network environment may be created from a healthy node or a restored healthy node. The creation of the new cluster network environment may be based at least in part on cluster configuration data.

Abstract: There is provided a method of, and apparatus for, enabling data recovery on a data storage resource. The resource includes a file system having a file system structure component for data storage management. In use, a storage request operable to modify the file system is received, processed and the file system structure component updated based on the storage request. Subsequently, a data record recording the modification by the storage request is generated and used to update an auxiliary file system structure component separate from the file system structure component. By providing such a method, a file system structure can be recreated and recovered quickly after a failure or error utilising the auxiliary file system structure component. This enables a file system to be reconstructed much faster than conventional approaches because the auxiliary file system structure has already been created.

Abstract: An image outputting apparatus obtains attribute information about image data prior to acquisition of the image data stored in an external apparatus. The image outputting apparatus accepts an output request of the image data by using the attribute information while obtaining the image data. The image outputting apparatus holds the output request in accordance with the acceptance of the output request before completion of acquisition of the image data and allows the outputting the image data in response to the output request after acquisition of the image data has been completed.

Abstract: This invention involves tracking and backing all the information that a user generates on its computer devices (including embedded devices) in real time. The local user server records all user actions and gestures (via various means that include TV cameras). All of this information (user actions and saved files in a computer) is then sent to a remote server via the Internet. This remote server has a virtual map of all the embedded devices on a computer that the person uses. The remote server immediately starts to interpret the user's actions (including user gestures). In one implementation, the invention stores user actions that are related to data generation (e.g. actions that called some links where data is stored, or executed some programs that generated data). In another variant the remote server generates and downloads the same files that are downloaded on the local user computer devices.

Abstract: Aspects of the present invention are directed to a system for next day reconciliation of transportation records. The system having a transportation record storage provider (TRSP) that receives and stores storage medium transportation requests; an outside service provider (OSP) inventory manager that receives and maintains records of transported storage mediums scanned at the OSP; and a reconciliation provider that receives a first list from the TRSP and a second list from the OSP inventory manger, for reconciliation. The reconciliation provider includes receivers for receiving the first and second list; a processing engine that reconciles the first list and the second list; and a reporting unit that reports the results of the reconciliation. The processing engine matches inbound and outbound records of the first list and second list, and processes invalid records; and analyzes and accounts for un-matched records.

Abstract: A method is used in controlling multi-step storage management operations. From a specification of a desired configuration of a data storage system, a description of a multi-step transaction for producing the desired configuration is derived. The description includes directions for reacting to results of an intermediate step within the multi-step transaction. Management operations are invoked based on the description.

Abstract: Methods, apparatuses, and computer program products are provided for database record recovery. A method may include determining a target database record format. The method may further include using the target database record format to evaluate source data for presence of database records matching the target database record format. The method may additionally include, in an instance in which a database record is determined, based on the evaluation, to be present in the source data, recovering the database record from the source data. Corresponding apparatuses and computer program products are also provided.

Abstract: A secondary location is configured as a recovery service for a primary location of the service. The secondary location is maintained in a warm state that is configured to replace the primary location in a case of a failover. During normal operation, the secondary location is automatically updated to reflect a current state of the primary location that is actively servicing user load. Content changes to the primary location are automatically reflected to the secondary location. System changes applied to the primary location are automatically applied to the secondary location. For example, removing/adding machines, updating machine/role assignments, removing adding/database are automatically applied to the secondary location such that the secondary location substantially mirrors the primary location. After a failover to the secondary location, the secondary location becomes the primary location and begins to actively service the user load.

Abstract: A method, system, and computer program product for reduplicating data in a data storage system is provided. The method includes retrieving a restore set in response to receiving a request to restore deduplicated data, identifying the deduplicated data in the restore set, creating a list of unique data block identifiers for the deduplicated data, and restoring the deduplicated data into a target location by downloading only block data content from a storage node that corresponds to the unique list of data block identifiers.

Abstract: A system (and a method) is disclosed to extract entity values from texts. The system receives, at a first tier entity recognition engine, an input data string having a plurality of entities. The first tier entity recognition engine marks entities of the plurality of entities that are regular expression and transmits the input data stream with the marked entities to a second tier entity recognition engine. The second tier entity recognition engine receives the input data stream and identifies unmarked entities in the input data stream received at the second tier entity recognition engine. The second tier entity recognition engine determines whether the unmarked entities comprise a predetermined data format, and if so, outputs those unmarked entities of the plurality of entities that comprise the predetermined data format.

Abstract: A method and apparatus for computing position using a regional-terrain model is provided. The method includes obtaining from at least three satellites pseudorange measurements, computing a transitional position by using a default altitude with a large uncertainty, using this transitional position to obtain from a terrain model altitude information associated with a region, and computing an accurate three-dimensional position as a function of the pseudorange measurements and the altitude information. The region defines a boundary, and the boundary includes the transitional position.

Abstract: One aspect of the present invention includes retrieving and recovering data chunks from alternate data stores in a storage management system which utilizes deduplication. In one embodiment, deduplication information for data chunks of data objects is stored at a system-wide level to enable the transfer and access of data chunks stored among multiple storage pools. When a data object is accessed on a first storage pool that contains damaged or inaccessible data chunks, the undamaged and accessible chunks may be retrieved from the first storage pool, in addition to retrieving an undamaged copy of the damaged or inaccessible data chunks from alternate data storage pools. Thus, a complete data object can be retrieved or recovered with a combination of chunks from the first storage pool and other storage pools within the storage management system, without requiring the entire data object to be retrieved from a backup source.

Abstract: Provided are computer program product, system, and method for restoring deduplicated data objects from sequential backup devices. A server stores data objects of extents having deduplicated data in the at least one sequential backup device. The server receives from a client a request for data objects. The server determines extents stored in the at least one sequential backup device for the requested data objects. The server or client sorts the extents according to an order in which they are stored in the at least one sequential backup device to generate a sort list. The server retrieves the extents from the at least one sequential backup device according to the order in the sort list to access the extents sequentially from the sequential backup device in the order in which they were stored. The server returns the retrieved extents to the client and the client reconstructs the requested data objects from the received extents.

Abstract: A computer system and restoration method that can facilitate restoration work is suggested. A management server collects necessary information from at least a business server, a storage apparatus with a primary volume formed therein, and a storage apparatus with a secondary volume formed therein; calculates, in response to a restoration request given externally, restoration time required for execution of requested restoration processing by each of a plurality of types of predetermined restoration methods based on the information collected by an information collecting unit; decides a restoration method with the shortest restoration time to be the restoration method for the restoration processing to be executed in response to the restoration request; and notifies the business server of the decided restoration method.

Abstract: Systems and methods are disclosed for recovering data following a directory service malfunction, such as a forest-wide disaster in Microsoft® Active Directory. In certain examples, a single management console can be used for remotely recovering selected domain controllers in the forest without necessitating direct operator intervention. Multiple domain controllers can be concurrently restored from one or more backup files. Configurations of the system can advantageously eliminate manual intervention with each domain controller, thereby saving significant amounts of recovery time and effort. Also, certain systems and methods can be used to automatically and remotely quarantine corrupt domain controllers so that those individual domain controllers do not replicate with the newly restored environment, while allowing the domain controllers to remain online and in communication with the attached network.

Abstract: In one embodiment, a service mediator provides a service that is a composite of atomic services and executes a recovery pattern in the event that a service is not available. More particularly, in an initial phase of operation, the service mediator determines one or more recovery patterns for each atomic service offered in the composite service and stores in a database an identity of each such recovery pattern for each atomic service. In subsequent operation, the service mediator monitors the availability of each atomic service. When a user inquires of a composite service, the service mediator determines if any of its atomic services is unavailable. If an atomic service is unavailable, the service mediator selects a recovery pattern and executes it.

Abstract: Provided are computer program product, system, and method for restoring deduplicated data objects from sequential backup devices. A server stores data objects of extents having deduplicated data in the at least one sequential backup device. The server receives from a client a request for data objects. The server determines extents stored in the at least one sequential backup device for the requested data objects. The server or client sorts the extents according to an order in which they are stored in the at least one sequential backup device to generate a sort list. The server retrieves the extents from the at least one sequential backup device according to the order in the sort list to access the extents sequentially from the sequential backup device in the order in which they were stored. The server returns the retrieved extents to the client and the client reconstructs the requested data objects from the received extents.

Abstract: Provided are a method, system, and article of manufacture for managing metadata for data blocks used in a deduplication system. File metadata is maintained for files having data blocks in a computer readable device. Data block metadata is maintained for each data block in the computer readable device. The data block metadata for one data block includes a data block reference and content identifier identifying content of the data block. The file metadata for each file includes the data block reference to each data block in the file. A determination is made of an unreferenced data block in the computer readable device that has become unreferenced. Indication is made that the data block metadata for the determined unreferenced data block as unreferenced metadata. The data block reference of the unreferenced metadata is maintained in the computer readable device in response to determining that a includes the data block indicated in the unreferenced metadata.