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: Embodiments disclosed herein provide systems, methods, and computer-readable media to implement an object store with removable storage media. In a particular embodiment, a method provides identifying first data for storage on a first removable storage medium and designating at least a portion of the first data to a first data object. The method further provides determining a first location where to store the first data object in a first value store partition of the first removable storage medium and writing the first data object to the first location. Also, the method provides writing a first key that identifies the first data object and indicates the first location to a first key store partition of the first removable storage medium.

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 circuits that produce EC encoded data that has a likelihood of use, that select a location to store the EC encoded data in the DSS based on the energy efficiency rating, the latency, or the likelihood of use, that store the EC encoded data in the location, and that compute an order of retrieval for EC encoded data stored in the location. The order of retrieval may be based on the energy efficiency rating or the latency. The EC encoded data may also have a priority based on the number of erasures for which the EC corrects.

Abstract: A technique includes in a data storage device, sensing a plurality of data streams from a track of storage media as the media moves in a given direction using a plurality of read elements such that at least one of the read elements is redundant. The technique includes combining the data streams to generate a data stream indicating data read from the track.

Abstract: Example apparatus and methods combine erasure coding with data deduplication to simultaneously reduce the overall redundancy in data while increasing the redundancy of unique data. In one embodiment, an efficient representation of a data set is produced by deduplication. The efficient representation reduces duplicate data in the data set. Redundancy is then added back into the data set using erasure coding. The redundancy that is added back in adds protection to the unique data associated with the efficient representation. How much redundancy is added back in and what type of redundancy is added back in may be controlled based on an attribute (e.g., value, reference count, symbol size, number of symbols) of the unique data. Decisions concerning how much and what type of redundancy to add back in may be adapted over time based, for example, on observations of the efficiency of the overall system.

Abstract: Example apparatus and methods combine erasure coding with data deduplication to simultaneously reduce the overall redundancy in data while increasing the redundancy of unique data. In one embodiment, an efficient representation of a data set is produced by deduplication. The efficient representation reduces duplicate data in the data set. Redundancy is then added back into the data set using erasure coding. The redundancy that is added back in adds protection to the unique data associated with the efficient representation. How much redundancy is added back in and what type of redundancy is added back in may be controlled based on an attribute (e.g., value, reference count, symbol size, number of symbols) of the unique data. Decisions concerning how much and what type of redundancy to add back in may be adapted over time based, for example, on observations of the efficiency of the overall system.

Abstract: Embodiments include a data aware deduplicating object store. The data aware deduplicating data store includes a consistent hashing logic that manages a consistent hashing architecture for the object store. The consistent hashing architecture includes a metadata ring and a bulk ring. The consistent hashing architecture may be a multiple ring architecture comprising a metadata ring and two or more bulk rings. A bulk ring may include a key/value (k/v) data store, where a k/v data store stores a shard of an index and a reference count that facilitates the individual approach to garbage collection or data reclamation. The data aware deduplicating data store also includes a deduplication logic that provides data deduplication for data to be stored in the object store. The deduplication logic performs variable length deduplication and provides a shared nothing approach.

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: Example apparatus and methods combine erasure coding with data deduplication to simultaneously reduce the overall redundancy in data while increasing the redundancy of unique data. In one embodiment, an efficient representation of a data set is produced by deduplication. The efficient representation reduces duplicate data in the data set. Redundancy is then added back into the data set using erasure coding. The redundancy that is added back in adds protection to the unique data associated with the efficient representation. How much redundancy is added back in and what type of redundancy is added back in may be controlled based on an attribute (e.g., value, reference count, symbol size, number of symbols) of the unique data. Decisions concerning how much and what type of redundancy to add back in may be adapted over time based, for example, on observations of the efficiency of the overall system.

Abstract: Example apparatus and methods combine erasure coding with data deduplication to simultaneously reduce the overall redundancy in data while increasing the redundancy of unique data. In one embodiment, an efficient representation of a data set is produced by deduplication. The efficient representation reduces duplicate data in the data set. Redundancy is then added back into the data set using erasure coding. The redundancy that is added back in adds protection to the unique data associated with the efficient representation. How much redundancy is added back in and what type of redundancy is added back in may be controlled based on an attribute (e.g., value, reference count, symbol size, number of symbols) of the unique data. Decisions concerning how much and what type of redundancy to add back in may be adapted over time based, for example, on observations of the efficiency of the overall system.

Abstract: Example apparatus and methods selectively generate and store erasure codes differently based on priorities associated with the erasure codes or based on conditions in a data storage system (DSS) that protects messages using erasure codes. Producing a systematic erasure code (EC) may be prioritized over producing a non-systematic EC. Producing an EC associated with correcting X erasures may be prioritized over producing an EC associated with correcting Y erasures, X and Y being numbers, X<Y. The priorities may depend on conditions in the DSS including an erasure code A/B policy, numbers of errors experienced by the DSS, types of errors experienced by the DSS, frequency of errors, an amount of power required to store or retrieve an EC in the DSS, or a network bandwidth required to store or retrieve an EC in the DSS. The priorities may be user configurable or self-adapting.

Abstract: Methods, apparatus, and other embodiments associated with doubly distributing erasure encoded data in a data storage system are described. One example apparatus includes a set of data storage devices and a set of logics that includes an encoding logic that generates an erasure encoded object that includes code-words, and chunks the code-words into code-word chunks, and a distribution logic that interleaves members of the set of code-word chunks into a plurality of records, and distributes the records across the data storage devices and within individual data storage devices. Example apparatus may include a read logic that reads the plurality of stored records from the data storage devices, and ignores read errors, and a repair logic that monitors the set of data storage devices, replaces or repairs failing data storage devices, generates replacement records, and stores the replacement records on a replacement data storage device.

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 circuits that produce EC encoded data that has a likelihood of use, that select a location to store the EC encoded data in the DSS based on the energy efficiency rating, the latency, or the likelihood of use, that store the EC encoded data in the location, and that compute an order of retrieval for EC encoded data stored in the location. The order of retrieval may be based on the energy efficiency rating or the latency. The EC encoded data may also have a priority based on the number of erasures for which the EC corrects.

Abstract: Example apparatus and methods selectively generate and store erasure codes differently based on priorities associated with the erasure codes or based on conditions in a data storage system (DSS) that protects messages using erasure codes. Producing a systematic erasure code (EC) may be prioritized over producing a non-systematic EC. Producing an EC associated with correcting X erasures may be prioritized over producing an EC associated with correcting Y erasures, X and Y being numbers, X<Y. The priorities may depend on conditions in the DSS including an erasure code A/B policy, numbers of errors experienced by the DSS, types of errors experienced by the DSS, frequency of errors, an amount of power required to store or retrieve an EC in the DSS, or a network bandwidth required to store or retrieve an EC in the DSS. The priorities may be user configurable or self-adapting.

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: 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 combine erasure coding with data deduplication to simultaneously reduce the overall redundancy in data while increasing the redundancy of unique data. In one embodiment, an efficient representation of a data set is produced by deduplication. The efficient representation reduces duplicate data in the data set. Redundancy is then added back into the data set using erasure coding. The redundancy that is added back in adds protection to the unique data associated with the efficient representation. How much redundancy is added back in and what type of redundancy is added back in may be controlled based on an attribute (e.g., value, reference count, symbol size, number of symbols) of the unique data. Decisions concerning how much and what type of redundancy to add back in may be adapted over time based, for example, on observations of the efficiency of the overall system.

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: 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.