Abstract: A data storage structure, comprising: a plurality of storage units, each comprising: a storage media; and a library executive configured to manage the storage media. The structure further comprises a buffer connected to a controller, the controller comprising: a host interface configured to receive the instruction from the host machine; an object aggregator configured to combine the plurality of data objects into a data segment; a persistent write buffer configured to store the data segment; a persistent map configured to identify a location of each of the plurality of objects in the data segment; an erasure coder configured to encode the data segment into an erasure code; a destager configured to transfer the data segment from the persistent write buffer to the storage media in a given storage unit; and a library controller configured to communicate with the library executive in the given storage unit.

Abstract: One embodiment provides a method for reclaiming free space. The method comprises selecting a first blob for reclamation from a first data center; sending a first message to a second data center indicating the first blob is to be reclaimed; sending a second message to the second data center after reclaiming the first blob; receiving a global reclamation complete message from the second data center; reading at least one data set from the first blob; and storing in a write buffer the at least one data set for encoding into a erasure code group in an alternative blob in the first data center. Further, upon receipt of the global reclamation message from the second data center, indicating the first blob is free in the map in the first data center. In one embodiment, selecting the first blob is based on the map indicating free space in the first data center.

Abstract: Embodiments relate to a computer system for storing data on a time multiplexed redundant array of independent tapes. An aspect includes a memory device that buffers data received by the computer system to be written to a set of tape data storage devices. The data is written to the set of tape data storage devices in blocks that form parity stripes across the set of tape data storage device. Aspects further includes a tape drive that writes data to one of the set of tape data storage devices at a time in a tape-sequential manner and a processor that computes a parity value for each of the parity stripes. The tape drive writes the parity values for each of the parity stripes to a last subset of tapes of the set of tape data storage devices.

Abstract: Embodiments of the invention provide parity logs for raid systems with variable-capacity media. In one embodiment, a system includes a first set of data storage media devices having variable capacity. The storage devices include a data portion of a parity data set for storing write data being striped to the first. The system further includes a second set of data storage media devices having variable capacity. The second set includes a linear address space of blocks for storing a parity portion of the parity data set. The linear address space is written in a log form. The first and second sets comprise at least one array in a RAID configuration. The system writes the parity portion of the parity data set to the second set, which enables each storage device among the first set to be written to full capacity.

Abstract: Embodiments of the invention relate to receiving a write request that includes a write data and an address of a target block in tertiary storage. In response to the write request, a write-miss is detected at a cache located in persistent storage. Based on detecting the write-miss, the write data and associated metadata are written to a fast write storage location and the write request is marked as complete. In addition, the target block is retrieved from the address in the tertiary storage and stored in the cache. Contents of the fast write storage location are merged with the contents of the target block in the cache.

Abstract: Embodiments of the invention relate to cache management of sequential write storage. Cache states of cache blocks in cache storage are tracked. The tracking incudes creating a migration candidate list that organizes the cache blocks into virtual volumes. Based on determining that a cache migration threshold has been reached, at least a subset of the cache blocks are selected from the migration candidate list for migration. The selected cache blocks are ordered into a sequential order based on the migration candidate list. At least a subset of the selected cache blocks are migrated in the sequential order, the migrating including writing contents of the selected cache blocks to the sequential write storage.

Abstract: Embodiments of the invention provide parity logs for raid systems with variable-capacity media. In one embodiment, a system includes a first set of data storage media devices having variable capacity. The storage devices include a data portion of a parity data set for storing write data being striped to the first. The system further includes a second set of data storage media devices having variable capacity. The second set includes a linear address space of blocks for storing a parity portion of the parity data set. The linear address space is written in a log form. The first and second sets comprise at least one array in a RAID configuration. The system writes the parity portion of the parity data set to the second set, which enables each storage device among the first set to be written to full capacity.

Abstract: Embodiments relate to a computer system for storing data on a time multiplexed redundant array of independent tapes. An aspect includes a memory device that buffers data received by the computer system to be written to a set of tape data storage devices. The data is written to the set of tape data storage devices in blocks that form parity stripes across the set of tape data storage device. Aspects further includes a tape drive that writes data to one of the set of tape data storage devices at a time in a tape-sequential manner and a processor that computes a parity value for each of the parity stripes. The tape drive writes the parity values for each of the parity stripes to a last subset of tapes of the set of tape data storage devices.

Abstract: Embodiments of the invention relate to cache management of sequential write storage. Cache states of cache blocks in cache storage are tracked. The tracking incudes creating a migration candidate list that organizes the cache blocks into virtual volumes. Based on determining that a cache migration threshold has been reached, at least a subset of the cache blocks are selected from the migration candidate list for migration. The selected cache blocks are ordered into a sequential order based on the migration candidate list. At least a subset of the selected cache blocks are migrated in the sequential order, the migrating including writing contents of the selected cache blocks to the sequential write storage.

Abstract: One aspect of the present invention provides an operation for recovering lost space and maintaining data consistency in a storage environment by providing a two-way orphan reconciliation method for extremely large file systems, such as a Hierarchical Storage Management (HSM) system which manages billions of files. This highly scalable and parallelizable orphan identification process may be used in a HSM controlled environment to enable the execution of a two-way file orphan check. In one embodiment, this orphan check identifies file system client orphans and server object orphans in a single pass by comparing a queue containing a list of migrated files on a storage repository server with a queue containing a list of stub files on a file system. If the queue elements do not match, a file system orphan or server object orphan can appropriately be identified.

Abstract: A method of synchronous deletion of managed files in a file system includes receiving a destroy event for a file to be deleted from the file system, the destroy event being generated upon request to destroy a file or corresponding objects of the files system; processing the received destroy event. Processing the destroy event includes determining if hierarchical storage management of the file system is initiated, and if initiated, continuing processing of the received destroy event; blocking threads indefinitely for an event storm during processing of the received destroy event; determining if the file to be deleted is being premigrated, migrated or is being recalled; aborting migration of the file based on the determination of migration and recall; and deleting the file and server objects corresponding to the file from the file system, where initiation of file deletion and server object deletion are synchronous.

Abstract: One aspect of the present invention provides an operation for recovering lost space and maintaining data consistency in a storage environment by providing a two-way orphan reconciliation method for extremely large file systems, such as a Hierarchical Storage Management (HSM) system which manages billions of files. This highly scalable and parallelizable orphan identification process may be used in a HSM controlled environment to enable the execution of a two-way file orphan check. In one embodiment, this orphan check identifies file system client orphans and server object orphans in a single pass by comparing a queue containing a list of migrated files on a storage repository server with a queue containing a list of stub files on a file system. If the queue elements do not match, a file system orphan or server object orphan can appropriately be identified.