Abstract: Example apparatus and methods provide a file system that stores files in multiple different logical units. The logical units are associated with different classes of devices. The file system interacts with the logical units through block-based interfaces. The file system is a single file system that spans the multiple logical units. The multiple different logical units include data storage devices for which the file system manages block storage allocation and an object storage system that manages its own block storage allocation rather than having the file system manage its block storage allocation. The file system may maintain a single namespace, hierarchy, or directory structure for the multiple logical units. The object storage system may protect files using redundant copies, erasure codes, or other approaches. An archive process may selectively move files from other devices to the object storage system and leave a symbolic link behind.

Abstract: Example apparatus and methods reserve space in a journal using an observation based approach instead of a fixed sized approach or a worst case scenario approach. One example method receives a request to allocate space in a journal to support a file system transaction. The example method reserves an amount of space in the journal based on a pre-existing reservation size estimate. Unlike conventional systems, the estimate is not based on a worst-case scenario. The example method observes the actual amount of storage used in the journal by the file system transaction and then selectively automatically adjusts the pre-existing reservation size estimate. The estimate may slowly shrink if no overflows are encountered but may quickly grow if an overflow is detected.

Abstract: Example apparatus and methods concern metadata peering that allows a file system to address a file in a local namespace while actually accessing the file using an address used by a shared secondary storage. This allows the file system to operate unmodified and more efficiently in a native mode that addresses files in the shared secondary storage using addresses local to a computer running the file system. An example method accesses an inode associated with a file that is stored in a shared secondary storage. The method accesses a local namespace identifier used by the file system to access the file and accesses a reference used by the shared secondary storage to access the file. The reference is not associated with the local namespace. The method stores an opaque value in the inode. The opaque value facilitates accessing the file in the shared secondary storage using the local namespace.

Abstract: Methods, apparatus, and other embodiments facilitate transitioning a database between two modes. The two modes include a mode where table information for separate tables in the database is stored in a single monolithic file and a mode where the table information for separate tables is stored in separate files. Conventional attempts to make this type of transition lock the database for an unacceptable amount of time. Example methods and apparatus make a copy of a database that is to be transitioned, lock the copy, make a second instance of the copy, and then perform the work necessary for the transition in the second instance. This allows the original database to remain running. When the second instance is complete, the second instance is synchronized to the original database and then the transition is completed by copying the second instance to the original or failing the original over to the second instance.

Abstract: Methods and apparatus deduplicate and erasure code a message in a data storage system. One example apparatus includes a first chunking circuit that generates a set of data chunks from a message, an outer precoding circuit that generates a set of precoded data chunks and a set of parity symbols from the set of data chunks, a second chunking circuit that generates a set of chunked parity symbols from the set of parity symbols, a deduplication circuit that generates a set of deduplicated data chunks by deduplicating the set of precoded chunks or the set of chunked parity symbols, an unequal error protection (UEP) circuit that generates an encoded message from the set of deduplicated data chunks, and a storage circuit that controls the data storage system to store the set of deduplicated data chunks, the set of parity symbols, or the encoded message.

Abstract: A magnetic tape for use in a tape drive includes a plurality of tracks and a plurality of media defect characteristics. The plurality of tracks are laid out along a length of the magnetic tape, each of the plurality of tracks being configured to receive data that is organized into a plurality of fixed-size subdata sets each including a plurality of codeword interleaves. The data is laid out on the plurality of tracks in accordance with a tape layout allocation strategy as determined by a tape layout module. The tape layout module includes a tape layout optimization system that receives information on the plurality of media defect characteristics, the tape layout optimization system determining the tape layout allocation strategy based at least in part on at least one of the plurality of media defect characteristics; and the tape layout optimization system determining the tape layout allocation strategy further based on distance spectra between pairs of the plurality of codeword interleaves.

Abstract: Embodiments disclosed herein provide systems and method for storing metadata to unused portions of a virtual disk file. In a particular embodiment, a method provides selecting a virtual disk file stored on a data storage volume and identifying unused portions of the virtual disk file. The method further provides writing metadata for the virtual disk file in the unused portions of the virtual disk file.

Abstract: Example apparatus and methods provide a log structured block device for a hard disk drive (HDD). Data that is to be stored on an HDD is serialized and written as a series of data blocks using a sequential write. Information about where individual data blocks were supposed to be written (e.g., actual address, neighboring data blocks), where data blocks were actually written, and how often data blocks are accessed is maintained. During garbage collection, data blocks that are being accessed with similar frequencies may be relocated together, with the most frequently accessed (e.g., hottest) data blocks migrating to the outer cylinders of the disk and the least frequently accessed (e.g., coldest) data blocks migrating to the inner cylinders. Blocks stored in the same temperature regions that were intended to be located together when written may be repositioned to facilitate sequential reads.

Abstract: Methods and apparatus associated with data cold storage are described. Example apparatus include an array of data storage devices arranged in rows and columns. Columns of the array are orthogonal to rows. A row has an associated row-centric power supply, and a column has an associated column-centric local electronics module (LEM) that controls a data storage device in the column independently of other data storage devices in the array. Example apparatus include logics that control a power mode of a data storage device independently of other data storage devices in the array, that control a power mode of an LEM, that adaptively regulate the level of data stored in a buffer, and that determine whether a data object will be stored in the buffer or stored on a data storage device in the array, based on the probability the data object will be accessed within a threshold period of time.

Abstract: Example apparatus and methods access a Linear Tape File System (LTFS) repository that stores data associated with an external entity (e.g., file system, application). Data is copied from the LTFS repository, selectively converted to a form associated with a cloud repository, and provided to the cloud repository. A mapping between corresponding addresses in the LTFS repository and cloud repository is established. Requests by the external entity for data may be satisfied from either the LTFS repository or the cloud repository until a changeover event is detected and are then satisfied from the cloud repository afterwards. The external entity runs on a different computer than the method. The method is transparent to the external entity, is performed independent of the external entity, and continues under its own control until a selected amount of data is moved from the LTFS repository to the cloud repository.

Abstract: Example apparatus, methods, and computers control configurable, variable data reduction. One example method includes identifying data reduction controlling attributes in an object to be data reduced by a configurable variable data reducer. The attributes provide information upon which decisions concerning whether and/or how to data reduce the object can be based. The example method also includes controlling a configurable variable data reducer to selectively data reduce the object based, at least in part, on the data reduction controlling attributes. The control exercised can determine whether, where, when, and/or how data reduction will proceed.

Abstract: Storage conditioning for a data storage system having D data storage devices (DSDs) is provided. E erasure codes (ECs) for an object are stored in the system, D>E. A map of d E-sized vectors of the D DSDs is produced. A DSD appears in e vectors. The ratio d/e is the reduced form of D/E. A hash value is produced for the object. A destination vector for storing the ECs is selected using the hash value according to a pre-determined, substantially uniform distribution. A compromised vector affected by a first DSD becoming unable to store ECs is identified. An intact vector that is not affected by the first DSD is identified. A complete set of ECs is produced from an incomplete set of ECs in the compromised vector and is distributed to the intact vector then copied back when the compromised vector is once again intact.

Abstract: Example apparatus and methods create and maintain a functional mirror of file system metadata for an active file system. The functional mirror may be implemented as a set of feature vectors in a feature space stored in a spatial database that allow a journal functionality for information received from the active file system. Mirror creation and maintenance can operate in parallel. The functional mirror may be created primarily using a systematic, system-wide, multi-threaded crawler approach whose results are updated using an event-driven approach that accounts for changes that may obsolete information acquired during the crawler approach. Transaction identifiers may be stored and potentially obsolete information preserved to facilitate providing views and rewind features.

Abstract: Methods and apparatus associated with storing data in high or low energy zones are described. Example apparatus include a data storage system (DSS) that protects a message using an erasure code (EC). A location in the DSS may have an energy efficiency rating or a latency. Example apparatus include logics that produce an EC that has a likelihood of use, that select a location to store the EC in the DSS based on the energy efficiency rating, the latency, or the likelihood of use, that store the EC in the location, and that compute an order of retrieval for an EC stored in the location. The order of retrieval may be based on the energy efficiency rating or the latency. The EC may also have a priority based on the number of erasures for which the EC corrects.

Abstract: Embodiments disclosed herein provide systems and methods for performing garbage collection in virtual environments. In a particular embodiment, a method provides performing a garbage collection process to identify at least a portion of a secondary storage volume located within a primary storage volume. The method further provides triggering a data block release process on at least a portion of the primary storage volume corresponding to the at least a portion of the secondary storage volume.

Abstract: Example apparatus and methods monitor conditions in a tiered storage system. The conditions monitored may include the availability of different numbers and types of devices including an erasure code based object storage system. The conditions monitored may also include the availability and type of devices available to the erasure code based object storage system. A redundancy policy for storing an item using the erasure code based object storage system may be determined based on the conditions. Erasure codes associated with the item may then be stored in the erasure code based object storage system as controlled, at least in part, by the redundancy policy. The redundancy policy for the erasure codes may be updated dynamically in response to changing conditions on the tiered storage system.

Abstract: Methods, apparatus, and other embodiments associated with adaptive use of erasure codes for distributed data storage systems are described. One example method includes accessing a message, where the message has a message size, selecting an encoding strategy as a function of the message size, data storage device failure statistics, data storage device wear periods, data storage space constraints, or overhead constraints, and where the encoding strategy includes an erasure code approach, generating an encoded message using the encoding strategy, generating an encoded block, where the encoded block includes the encoded message and metadata associated with the message, and storing the encoded block in the data storage system. Example methods and apparatus may employ Reed Solomon erasure codes or Fountain erasure codes. Example methods and apparatus may display to a user the storage capacity and durability of the data storage system.

Abstract: Embodiments disclosed herein provide systems, methods, and computer readable media to handle unsuccessful movements of removable storage media in an automated removable media system. In a particular embodiment, a method provides receiving one or more user provided parameters that indicate one or more types of unsuccessful media move operations that should be reported as successful. The method further provides receiving a first request to move a first item of removable storage media from a first position in the automated removable media system to a second position in the automated removable media system and initiating a first move operation of the first item from the first position to the second position by at least one changer device. The method then provides determining that the first move operation resulted in one of the one or more types of unsuccessful media move operations and indicating that the first move operation was successful in response to the first request.

Abstract: Apparatus and methods are provided herein for path lookup in a hierarchical file system. An inode associated with a requested object is identified. The inode may be organized in an inode table and identified in the table using an inode number. Ancestry information and size constraint information may also be available for the inode. An inode chain associated with the pathway is identified based, at least in part, on ancestry information associated with the inode for the requested object. A size constraint analysis is performed for the requested object. The size altering operation is selectively performed based on the size constraint analysis.