Abstract: According to one embodiment, a computer-implemented method includes receiving an object to be stored within a storage library, computing a hash value, utilizing the object, determining a storage location within the storage library to store the hash value, and sending the hash value to the storage location and neighbor locations of the storage location within the storage library.

Abstract: One embodiment provides a system including a computer processor, a computer-readable hardware storage device, and program code embodied with the computer-readable hardware storage device for execution by the computer processor to implement a method that includes receiving a selection of a first blob for reclamation from a first data center. The first blob includes multiple erasure code groups. A first message is sent to a second data center indicating the first blob is to be reclaimed. A global reclamation complete message is received from the second data center. The global reclamation complete message indicates a second blob in the second data center has been reclaimed. The first data center and the second data center each maintain local blob occupancy information.

Abstract: A computer-implemented method includes encoding an array of (p?1)×k symbols of data into a p×(k+r) array. The method includes p is a prime number, r?1, and k?p?r. The method also includes each column in the p×(k+r) array has an even parity and each line of slope j for 0?j?r?1 in the p×(k+r) array has an even parity. The method includes the lines of slope j taken with a toroidal topology modulo p. A computer program product for encoding an array of (p?1)×k symbols of data into a p×(k+r) array includes a computer readable storage medium having program instructions executable by a computer. The program instructions cause the computer to perform the foregoing method.

Abstract: One embodiment provides a method comprising maintaining, on a storage unit, mapping data between a first set of logical addresses (e.g., logical block addresses or LBAs) viewed by a host and a first set of physical addresses (e.g., physical block addresses or PBAs) and a second set of physical addresses of the storage unit. A first logical address (e.g., LBA) of the first set of logical addresses corresponds to a first physical address (e.g., PBA) of the first set of physical addresses that maintains current data for the first logical address. The first logical address further corresponds to a second physical address (e.g., PBA) of the second set of physical addresses that maintains prior data for the first logical address. The method further comprises receiving, at the storage unit, a command from the host to perform a multi-device operation involving the first logical address. The operation is performed atomically.

Abstract: A computer-implemented method includes encoding an array of (p?1)×k symbols of data into a p×(k+r) array. The method includes p is a prime number, r?1, and k?p. The method includes each column in the p×(k+r) array has an even parity and symbol i in column r+j, for 0?i?p?1 and 0?j?r?1, is the XOR of symbols in a line of slope j taken with a toroidal topology modulo p in the k columns starting in symbol i of column 0.

Abstract: According to one embodiment, a computer-implemented method includes determining a write speed for each of a plurality of systems in a cluster, determining a ratio of the write speeds for each of the plurality of systems in the cluster, and updating parity assignments to each of the plurality of systems in the cluster, based on the ratio of the write speeds.

Abstract: One embodiment provides a system including a computer processor, a computer-readable hardware storage device, and program code embodied with the computer-readable hardware storage device for execution by the computer processor to implement a method that includes receiving a selection of a first blob for reclamation from a first data center. The first blob includes multiple erasure code groups. A first message is sent to a second data center indicating the first blob is to be reclaimed. A global reclamation complete message is received from the second data center. The global reclamation complete message indicates a second blob in the second data center has been reclaimed. The first data center and the second data center each maintain local blob occupancy information.

Abstract: One embodiment provides a system including a computer processor, a computer-readable hardware storage device, and program code embodied with the computer-readable hardware storage device for execution by the computer processor to implement a method that includes selecting a first blob for reclamation from a first data center. The first blob includes multiple erasure code groups. A first message is sent to a second data center indicating the first blob is to be reclaimed. A second message is sent to the second data center after reclaiming the first blob in the first data center. A global reclamation complete message is received from the second data center. The global reclamation complete message indicates a second blob in the second data center has been reclaimed. The global reclamation complete message is sent in response to the second data center receiving a local reclamation complete message from a third data center.

Abstract: A computer-implemented method includes encoding an array of (p?1)×k symbols of data into a p×(k+r) array. The method includes p is a prime number, r?1, and k?p. The method includes each column in the p×(k+r) array has an even parity and symbol i in column r+j, for 0?i?p?1 and 0?j?r?1, is the XOR of symbols in a line of slope j taken with a toroidal topology modulo p in the k columns starting in symbol i of column 0.

Abstract: A method for memory page erasure-correcting property generation in a storage array includes dividing data into multiple stripes for storage in a storage array including multiple storage devices with a topology of a hypercube of a dimension t?3. The storage devices in same hypercubes of dimension t?1 including the hypercube of dimension t have even parity. An intersection of two non-parallel planes in the hypercube topology is a line, and each point along a line is a storage device in the storage array. Erasure-correcting properties are generated for the data using three nested codes, wherein a first nested code has even parity over planes of class 0, 1 and 2, a second nested code has a first global parity, and a third nested code has a second global parity and a third global parity.

Abstract: A computer-implemented method enables reconstructing contents of blocks in a storage system having l availability zones (AZs), a set of n storage units in each AZ arranged as columns, and a set of m storage blocks in each storage unit. The storage blocks of n+1 of the storage units are parity blocks, where l?1 of the AZs each include an additional parity block. The method includes using the parity blocks and/or data in the AZs and reconstructing contents of blocks in the storage system having l availability zones (AZs) from a concurrent loss of: one of the AZs, a storage unit together with one storage block in one of the remaining l?1 AZs, and one further storage block in each of the remaining l?2 AZs of the storage system.

Abstract: A computer-implemented method includes encoding an array of (p?1)×k symbols of data into a p×(k+r) array. The method includes p is a prime number, r?1, and k?p?r. The method also includes each column in the p×(k+r) array has an even parity and each line of slope j for 0?j?r?1 in the p×(k+r) array has an even parity. The method includes the lines of slope j taken with a toroidal topology modulo p. A computer program product for encoding an array of (p?1)×k symbols of data into a p×(k+r) array includes a computer readable storage medium having program instructions executable by a computer. The program instructions cause the computer to perform the foregoing method.

Abstract: According to one embodiment, a computer-implemented method includes receiving an object to be stored within a storage library, computing a hash value, utilizing the object, determining a storage location within the storage library to store the hash value, and sending the hash value to the storage location and neighbor locations of the storage location within the storage library.

Abstract: According to one embodiment, a computer-implemented method includes determining a write speed for each of a plurality of systems in a cluster, determining a ratio of the write speeds for each of the plurality of systems in the cluster, and updating parity assignments to each of the plurality of systems in the cluster, based on the ratio of the write speeds.

Abstract: A controller including an object aggregator process that combines multiple data objects into a data segment, and transfers the data segment with reduced location metadata to storage media of at least one of multiple storage units. An erasure coder process generates code to encode the data segment into an erasure code that protects against concurrent data loss in the multiple storage units based on data reconstruction using a first responder, a second responder and a last responder.

Abstract: A disc cassette includes a curved portion. The curved portion includes multiple ribs that define multiple disc slots. The disc slots are configured to hold multiple discs that are spaced apart by the ribs. The disc cassette further includes multiple index features positioned on an inside edge of the curved portion. The index features are configured to allow alignment of a kicker device of a disc retrieval unit (DRU) to a disc of the disc cassette to lift the disc into a disc gripper device without disturbing one or more other discs of the disc cassette that are adjacent to the disc.

Abstract: Embodiments relate to correcting erasures in a storage array. An aspect includes dividing data into a plurality of stripes for storage in a storage array comprising a plurality of storage locations, each stripe comprising M rows and N columns, each of the M rows including a number r of row parities, wherein r is greater than zero. Another aspect includes dividing each stripe into two or more column sets, each column set comprising a respective set of one or more columns of the stripe. Another aspect includes adding a respective first responder parity to each column set, wherein each first responder parity gives parity information for only the two or more columns in the first responder parity's respective column set.

Abstract: One embodiment provides a method comprising maintaining, on a storage unit, mapping data between a first set of logical addresses (e.g., logical block addresses or LBAs) viewed by a host and a first set of physical addresses (e.g., physical block addresses or PBAs) and a second set of physical addresses of the storage unit. A first logical address (e.g., LBA) of the first set of logical addresses corresponds to a first physical address (e.g., PBA) of the first set of physical addresses that maintains current data for the first logical address. The first logical address further corresponds to a second physical address (e.g., PBA) of the second set of physical addresses that maintains prior data for the first logical address. The method further comprises receiving, at the storage unit, a command from the host to perform a multi-device operation involving the first logical address. The operation is performed atomically.

Abstract: A disc cassette includes a curved portion configured to hold multiple discs. A platform portion abuts the curved portion. A movable bale is configured to maintain discs securely in the disc cassette except when rotated off the discs.

Abstract: A disc cassette includes a curved portion configured to hold multiple discs. The disc cassette further includes a bottom side including track connectors configured to position the disc cassette relative to one or more track portions that hold the disc cassette in place. The disc cassette is slideable along the one or more track portions.