Abstract: A data control system comprises a communication interface, a processing system, and a storage system. The communication interface is configured to receive a request to retrieve data from a primary storage volume that includes a secondary storage volume. The storage system is configured to store the primary storage volume that includes the secondary storage volume. The processing system is configured to identify changed segments of a plurality of segments in the primary storage volume and identify allocated segments of the changed segments. The communication interface is further configured to transfer the allocated segments in response to the request.

Abstract: Example apparatus and methods concern storing additional information about inodes to facilitate n-way inode translation between local inode spaces and external inode spaces. Example apparatus and methods also concern publishing information about actions that affect inodes to facilitate n-way inode translation. Additional data is added to local file systems so that a local file system can determine whether an inode for which an action is requested or reported is a native inode or an imported inode. The additional data added to the local file systems through the updated inode data storage and inode action publication also facilitates determining which local inode to act on based on the n-way inode translation mechanism.

Abstract: Disclosed are systems, methods, and software for performing version control. In a particular embodiment, a non-transitory computer readable medium is provided having stored therein program instructions that, when executed by a computer system, direct the computer system to perform a method of version control. The method includes executing a plurality of virtual machines from a plurality of derivative versions of an ancestor data volume, wherein the ancestor data volume and the plurality of derivative versions each comprise a plurality of files. The method further includes tracking modifications to the plurality of files in each of the plurality of derivative versions and merging the plurality of derivative versions with the ancestor data volume based on the modifications.

Abstract: Example apparatus and methods process data that is going to be stored in an object store. The object store may have multiple data destinations (e.g., “buckets”). Different buckets have different data storage policies that control, for example, how many copies of the data will be made, whether the data will be stored onsite or offsite, or other storage parameters. Data may be classified by identifying a value for an attribute (e.g., file type, file source) of the data. A storage policy associated with a bucket may then be selected based on the attribute. Once the storage policy has been selected, then the data may be provided to a bucket associated with the storage policy. The number of buckets, data classifications, or storage policies may be updated by adaptive parameterization that considers the amount or type of data observed and stored in the object store.

Abstract: Embodiments disclosed herein provide magnetic media access heads with metal coatings. In a particular embodiment, a magnetic media head for accessing magnetic media comprises a base substrate configured to support a magnetic head layer. The magnetic head layer is formed on the base substrate and configured to magnetically access the magnetic media. A metallic layer formed over the magnetic head layer and disposed between the magnetic head layer and the magnetic media when the magnetic media is positioned for access by the magnetic head layer.

Abstract: What is disclosed is a volume access system. The volume access system includes a processing system configured to process at least a portion of each of a plurality of virtual disk files to generate an aggregate file system view that represents the plurality of virtual disk files as a single hierarchical data volume comprising a plurality of items within the plurality of virtual disk files. The volume access system also includes a network interface operatively coupled with the processing system and configured to communicate the aggregate file system view for traversal by a plurality of clients.

Abstract: The present invention is directed toward methods and systems for data de-duplication. More particularly, in various embodiments, the present invention provides systems and methods for data de-duplication that may utilize a vectoring method for data de-duplication wherein a stream of data is divided into “data sets” or blocks. For each block, a code, such as a hash or cyclic redundancy code may be calculated and stored. The first block of the set may be written normally and its address and hash can be stored and noted. Subsequent block hashes may be compared with previously written block hashes.

Abstract: Example apparatus and methods monitor conditions in an object storage system. The conditions monitored may include a load balance measure in the system, a capacity balance measure in the system, a fault tolerance measure in the system, or a usage pattern measure in the system. A distribution plan or redistribution plan for storing or moving erasure codes in the object storage system may be determined based on the conditions. The distribution plan or the redistribution plan for the erasure codes may be updated dynamically in response to changing conditions in the object storage system. The distribution or redistribution may depend on a weighted combination of the load balance measure, the capacity balance measure, the fault tolerance measure, or the usage pattern measure so that responding to one sub-optimal condition (e.g., load imbalance) does not create a different sub-optimal condition (e.g., unacceptable fault tolerance).

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: Example apparatus and methods provide metadata for a file system operation from a multi-level data store. The data store may include an in-memory level one (L1) cache, an in-memory level two (L2) cache, and an external metadata store not located in the memory associated with the L1 and L2 caches. The L1 cache stores metadata in a non-compressed format that can directly service a file system operation while the L2 cache stores metadata in a compressed format that cannot directly service an operation. Metadata to support a file system operation may be sought in the L1 cache first, then in the L2 cache, and then finally in the external metadata store. When metadata is provided from the L2 cache, it is decompressed before being provided to the L1 cache. Metadata added to the L2 cache may be compressed after or in parallel with being provided to the L1 cache.

Abstract: The present invention is directed toward methods and systems for data de-duplication. More particularly, in various embodiments, the present invention provides systems and methods for data de-duplication that may utilize a vectoring method for data de-duplication wherein a stream of data is divided into “data sets” or blocks. For each block, a code, such as a hash or cyclic redundancy code may be calculated and stored. The first block of the set may be written normally and its address and hash can be stored and noted. Subsequent block hashes may be compared with previously written block hashes.

Abstract: The present invention is directed toward methods and systems for data de-duplication. More particularly, in various embodiments, the present invention provides systems and methods for data de-duplication that may utilize a vectoring method for data de-duplication wherein a stream of data is divided into “data sets” or blocks. For each block, a code, such as a hash or cyclic redundancy code may be calculated and stored. The first block of the set may be written normally and its address and hash can be stored and noted. Subsequent block hashes may be compared with previously written block hashes.

Abstract: A media drive includes a head, a servo signal processing circuit, an actuator and a processor. The head is positioned near a data storage medium, and includes a servo element. The servo signal processing circuit is coupled to the servo element to output a position error signal. The actuator controls a position of the head relative to the data storage medium. The processor communicates with the actuator and the servo signal processing circuit. The processor provides a filtered position error signal to the actuator to compensate for a position displacement between the head and the data storage medium. The filtered position error signal includes a sum of outputs from a first compensation filter and a second compensation filter that is each applied to the position error signal output. The compensation filters attenuate disturbance frequencies that contribute to the position displacement. Each of the compensation filters has a sampling rate relating to the respective disturbance frequency.

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 database tables that allow a journal functionality for information received from the active file system. Example apparatus and methods also restore the file system metadata from the functional mirror. Mirror creation and maintenance can operate in parallel. Mirror maintenance and metadata restore can also 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 make obsolete information acquired during the crawler approach. The metadata may be restored using a systematic, system-wide, multi-threaded crawler approach acting together with an event-driven approach that restores certain files out of order as they are needed.

Abstract: Responsive to an instruction to collapse a derivative version of an ancestor data volume into the ancestor data volume, it is determined if a characteristic of the derivative version of the ancestor data volume satisfies a criteria relative to a characteristic of the ancestor data volume. If the characteristic of the derivative version satisfies the criteria, the ancestor data volume is merged into the derivative version of the underlying data to form an updated derivative version. The updated derivative version is established as the ancestor data volume.

Abstract: Example apparatus and methods provide two types of storage for a virtual machine running on a hypervisor. The first storage is de-duplication based and the second storage is not de-duplication based. Example apparatus and methods may acquire data from the first storage to instantiate the virtual machine, to instantiate an operating system on the virtual machine, or to instantiate an application on the virtual machine from the first storage. Example apparatus and methods may write a snapshot to the second storage and then support random input/output for the virtual machine, for the operating system, or for the application from the second storage. The snapshot may selectively be collapsed or the second storage may selectively be retired and thus example systems may selectively update the first storage from the second storage. Having dual devices facilitates using de-duplication storage for de-duplication-centric I/O while non-de-duplication storage is used for random I/O.

Abstract: Embodiments disclosed herein provide magnetic media access heads with metal coatings. In a particular embodiment, a magnetic media head for accessing magnetic media comprises a base substrate configured to support a magnetic head layer. The magnetic head layer is formed on the base substrate and configured to magnetically access the magnetic media. A metallic layer formed over the magnetic head layer and disposed between the magnetic head layer and the magnetic media when the magnetic media is positioned for access by the magnetic head layer.

Abstract: A method for inhibiting cycle slip in a tape drive having at least three channels that each utilizes a corresponding numerically controlled oscillator includes establishing a reference clock that is based on an output of the numerically controlled oscillators for at least two of the channels, comparing the output of the numerically controlled oscillator for one of the three channels with the reference clock to determine a first channel phase delta value for the one channel, and generating an error signal for the one channel if the channel phase delta value exceeds a threshold phase delta value for the one channel.

Abstract: An apparatus and method for providing adaptive disturbance compensation with multi-rate synchronized sampling is disclosed herein. The dynamic disturbance occurring in a media drive during read/write operations is attenuated using the adaptive disturbance compensation scheme. A plurality of compensation filters are used, each of the compensation filters configured to attenuate a disturbance caused by a particular source within the media drive. Each of the compensation filters is computed based on a sampling rate relevant to the respective disturbances.

Abstract: A head rotator assembly (22) for dynamically compensating for a tape skew of a storage tape that moves over a head (20) in a tape drive (10) comprises a head supporter (230) that is coupled to and supports the head (20), and a supporter mover assembly (232). The supporter mover assembly (232) includes a first actuator (234A) that indirectly rotates a portion of the head supporter (230) about an axis to move the head (20) in an azimuth direction relative to the storage tape to dynamically compensate for the tape skew as the storage tape moves over the head (20). Additionally, the supporter mover assembly (232) can include a first lever (236A) moved by the first actuator (234A) to rotate the portion of the head supporter (230) so that the head (20) moves in the azimuth direction relative to the storage tape to dynamically compensate for the tape skew.