Abstract: Techniques are provided for implementing intelligent defragmentation in a storage system. A storage control system manages a logical address space of a storage volume. The logical address space is partitioned into a plurality of extents, wherein each extent comprises a contiguous block of logical addresses of the logical address space. The storage control system monitors input/output (I/O) operations for logical addresses associated with the extents, and estimates fragmentation levels of the extents based on metadata associated with the monitored I/O operations. The storage control system identifies one or more extents as candidates for defragmentation based at least on the estimated fragmentation levels of the extents.

Abstract: Techniques are provided to recover from partial device errors of storage devices in a data storage system. A storage control system manages a storage device which comprises storage capacity that is logically partitioned into segments of equal size. The storage control system groups at least some of the segments of the storage device into a segment group. Each segment of the segment group is configured to store one or more data items and associated metadata items. The storage control system generates a parity data segment based on the segments of the segment group, and persistently stores the parity data segment in association with the segment group. In response to detecting a storage device error associated with a corrupted segment of the segment group, the storage control system utilizes the parity data segment and non-corrupted segments of the segment group to recover at least one missing data item of the corrupted segment.

Abstract: An apparatus includes at least one processing device configured to identify a logical storage volume stored across multiple storage nodes of a distributed storage system, to obtain address range distribution information for the logical storage volume from at least a subset of the storage nodes, the address range distribution information indicating, for each of a plurality of distinct address ranges of the logical storage volume, which of the storage nodes locally stores data for that address range, and to generate, from the obtained address range distribution information, a mapping of the distinct address ranges to particular ones of the storage nodes, wherein the mapping is utilized to select paths for delivery of input-output operations to the storage nodes. Obtaining address range distribution information for the logical storage volume may comprise, for example, sending log page commands to each of the storage nodes to obtain asymmetric range access and/or template information.

Abstract: Techniques are provided for implementing intelligent defragmentation in a storage system. A storage control system manages a logical address space of a storage volume. The logical address space is partitioned into a plurality of extents, wherein each extent comprises a contiguous block of logical addresses of the logical address space. The storage control system monitors input/output (I/O) operations for logical addresses associated with the extents, and estimates fragmentation levels of the extents based on metadata associated with the monitored I/O operations. The storage control system identifies one or more extents as candidates for defragmentation based at least on the estimated fragmentation levels of the extents.

Abstract: A storage control system is configured to obtain first data associated with a logical data device and to store the first data in a first entry of a log-structured array. The storage control system is further configured to invalidate a second entry of the log-structured array based at least in part on the storage of the first data in the first entry. The second entry comprises second data that was associated with the logical data device prior to obtaining the first data. The storage control system is further configured to determine that a first indication in a first metadata indicates that the invalidated second entry corresponds to a transaction log and to defer reclamation of the second entry based at least in part on the determination that the first indication in the first metadata indicates that the invalidated second entry corresponds to the transaction log.

Abstract: An apparatus comprises at least one processing device comprising a processor coupled to memory. The at least one processing device is configured to obtain an input-output request issued by an application executing on a compute node via at least one network and to identify a storage node as corresponding to the obtained input-output request based at least in part on the obtained input-output request. The at least one processing device is configured to associate information corresponding to the compute node with the input-output request and to submit the input-output request and the associated information that corresponds to the compute node to the storage node via the at least one network. The storage node is configured to submit a response to the input-output request to the compute node via the at least one network based at least in part on the information.

Abstract: Techniques are provided for utilizing snapshot longevity information to manage snapshots in a snapshot-enabled storage system. A snapshot management system generates a snapshot volume tree which comprises snapshots associated with a given storage volume. The snapshot management system obtains a snapshot policy associated with the given storage volume, which comprises a snapshot creation and retention schedule that specifies retention lifespans of the snapshots. The snapshot policy is evaluated to automatically determine and assign respective longevity ranking values for the snapshots within the snapshot volume tree, wherein the longevity ranking value of a given snapshot represents a retention lifespan of the given snapshot as compared to retention lifespans of other snapshots as represented by their respective longevity ranking values.

Abstract: In some embodiments, a storage system comprises at least one processor coupled to memory. The processor is configured to obtain a write operation that comprises first data associated with a logical data device and to store the first data in a first entry of a log-structured array (LSA). The at least one processor is configured to invalidate a second entry based at least in part on the storage of the first data in the first entry. The second entry comprises second data associated with the logical data device that was stored in the second entry prior to obtaining the write operation. The at least one processor is configured to determine that a first indication in LSA metadata associated with the LSA indicates that the invalidated second entry comprises data that is awaiting replication and to defer reclamation of the second entry based at least in part on the determination.

Abstract: An apparatus comprising a processing device is configured to communicate with a storage node of a storage system via at least one network and to communicate with a compute node that implements at least a portion of an application via the at least one network. The at least one processing device is configured to obtain an input-output request associated with the application from the compute node via the at least one network and to associate information corresponding to the compute node with the input-output request. The at least one processing device is further configured to submit the input-output request and the associated information that corresponds to the compute node to the storage node. The storage node is configured to submit a response to the input-output request to the compute node via the at least one network based at least in part on the information.

Abstract: Techniques are provided to recover from partial device errors of storage devices in a data storage system. A storage control system manages a storage device which comprises storage capacity that is logically partitioned into segments of equal size. The storage control system groups at least some of the segments of the storage device into a segment group. Each segment of the segment group is configured to store one or more data items and associated metadata items. The storage control system generates a parity data segment based on the segments of the segment group, and persistently stores the parity data segment in association with the segment group. In response to detecting a storage device error associated with a corrupted segment of the segment group, the storage control system utilizes the parity data segment and non-corrupted segments of the segment group to recover at least one missing data item of the corrupted segment.

Abstract: An apparatus in an illustrative embodiment comprises at least one processing device comprising a processor coupled to a memory. The apparatus is configured to maintain a snapshot tree data structure having a plurality of volume nodes corresponding to respective ones of (i) a root volume and (ii) multiple snapshots related directly or indirectly to the root volume. The apparatus is further configured to receive a request to read a data item from a given volume offset of a particular one of the volume nodes, to determine a set of data descriptors for the given volume offset, to determine a set of volume nodes of interest for the particular volume node, to determine a contribution set based at least in part on the set of data descriptors and the set of volume nodes of interest, to determine a read address for the data item as a function of the contribution set, and to read the data item from the read address.

Abstract: An apparatus in an illustrative embodiment comprises at least one processing device comprising a processor coupled to a memory. The apparatus is configured to maintain a snapshot tree data structure having a plurality of volume nodes corresponding to respective ones of (i) a root volume and (ii) multiple snapshots related directly or indirectly to the root volume. The apparatus is further configured to determine a set of data descriptors for a given volume offset, to determine a set of reader volume nodes that are readers of a corresponding data item based at least in part on the set of data descriptors, to adjust one or more of the data descriptors in the set of data descriptors based at least in part on the set of reader volume nodes, and to reclaim storage space previously allocated to the data item responsive to the adjusting of the one or more data descriptors.

Abstract: Techniques are provided for utilizing snapshot longevity information to manage snapshots of storage volumes in a snapshot-enabled storage system. A snapshot management system maintains a snapshot volume tree which comprises a plurality of snapshots having respective longevity ranking values. The longevity ranking value of a given snapshot represents an expected life span of the given snapshot as compared to expected life spans of other snapshots as indicated by their respective longevity ranking values. When a snapshot is deleted, the snapshot management system determines a set of candidate snapshots which can assume ownership of uniquely-written data of the deleted snapshot, evaluates the longevity ranking values of the candidate snapshots to select a candidate snapshot to assume ownership of the uniquely-written data of the deleted snapshot, and modifies metadata of the selected snapshot to transfer the ownership of the uniquely-written data from the deleted snapshot to the selected snapshot.

Abstract: In some embodiments, a storage system comprises at least one processor coupled to memory. The processor is configured to obtain a write operation that comprises first data associated with a logical data device and to store the first data in a first entry of a log-structured array (LSA). The at least one processor is configured to invalidate a second entry based at least in part on the storage of the first data in the first entry. The second entry comprises second data associated with the logical data device that was stored in the second entry prior to obtaining the write operation. The at least one processor is configured to determine that a first indication in LSA metadata associated with the LSA indicates that the invalidated second entry comprises data that is awaiting replication and to defer reclamation of the second entry based at least in part on the determination.

Abstract: Techniques are provided for managing snapshot volume trees in a snapshot-enabled data storage system. A snapshot management system is configured to maintain a snapshot volume tree for a storage volume of a storage system, wherein the snapshot volume tree comprises a data structure which comprises a plurality of snapshot volume nodes corresponding to respective ones of (i) a root volume and (ii) multiple snapshots related directly or indirectly to the root volume, wherein the snapshot volume nodes comprise respective generation times which denote times that the respective snapshot volume nodes were created. The generation times are used in conjunction with write times of data items that are written to the snapshot volume nodes to manage snapshot reading and deletion operations.

Abstract: An apparatus comprising a processing device is configured to communicate with a storage node of a storage system via at least one network and to communicate with a compute node that implements at least a portion of an application via the at least one network. The at least one processing device is configured to obtain an input-output request associated with the application from the compute node via the at least one network and to associate information corresponding to the compute node with the input-output request. The at least one processing device is further configured to submit the input-output request and the associated information that corresponds to the compute node to the storage node. The storage node is configured to submit a response to the input-output request to the compute node via the at least one network based at least in part on the information.

Abstract: An apparatus comprises at least one processing device comprising a processor coupled to memory. The at least one processing device is configured to obtain an input-output request issued by an application executing on a compute node via at least one network and to identify a storage node as corresponding to the obtained input-output request based at least in part on the obtained input-output request. The at least one processing device is configured to associate information corresponding to the compute node with the input-output request and to submit the input-output request and the associated information that corresponds to the compute node to the storage node via the at least one network. The storage node is configured to submit a response to the input-output request to the compute node via the at least one network based at least in part on the information.

Abstract: A storage control system is configured to obtain first data associated with a logical data device and to store the first data in a first entry of a log-structured array. The storage control system is further configured to invalidate a second entry of the log-structured array based at least in part on the storage of the first data in the first entry. The second entry comprises second data that was associated with the logical data device prior to obtaining the first data. The storage control system is further configured to determine that a first indication in a first metadata indicates that the invalidated second entry corresponds to a transaction log and to defer reclamation of the second entry based at least in part on the determination that the first indication in the first metadata indicates that the invalidated second entry corresponds to the transaction log.

Abstract: A storage control system receives an I/O request from a client for accessing storage resources that are logically divided into device groups, and determines a resource token request value associated with the I/O request and a target device group to which the I/O request is directed. The storage control system determines a number of allowed resource tokens to allocate to the client as a function of (i) the resource token request value, (ii) a sum total of resource tokens requested by other clients for accessing the target device group, and (iii) a total amount of resource tokens currently allocated to the target device group to which the I/O request is directed. The storage control system sends the determined number of allowed resource tokens to the client to thereby enable the client to limit a number of inflight I/O requests that the client issues to the storage control system.

Abstract: An apparatus in an illustrative embodiment comprises at least one processing device comprising a processor coupled to a memory. The apparatus is configured to maintain a snapshot tree data structure having a plurality of volume nodes corresponding to respective ones of (i) a root volume and (ii) multiple snapshots related directly or indirectly to the root volume. The apparatus is further configured to determine a set of data descriptors for a given volume offset, to determine a set of reader volume nodes that are readers of a corresponding data item based at least in part on the set of data descriptors, to adjust one or more of the data descriptors in the set of data descriptors based at least in part on the set of reader volume nodes, and to reclaim storage space previously allocated to the data item responsive to the adjusting of the one or more data descriptors.