Abstract: A first storage system in one illustrative embodiment is configured to participate in a replication process with a second storage system. The first storage system detects a replication failure condition or other condition requiring termination of a synchronous replication mode of the replication process, and responsive to the detected condition, captures a snapshot of source data that is subject to replication from the first storage system to the second storage system as part of the replication process. The first storage system terminates the synchronous replication mode of the replication process, initiates an asynchronous replication mode of the replication process, executes an asynchronous-to-synchronous transition cycle scan operation for the replication process utilizing the captured snapshot, and resumes the synchronous replication mode of the replication process responsive to successful completion of the asynchronous-to-synchronous transition cycle scan operation.

Abstract: A storage system in one embodiment comprises a plurality of storage devices and a storage controller. The storage system is configured to implement a loopback replication process in which one or more source storage objects are replicated to one or more corresponding target storage objects within the storage system. The storage system is further configured to divide a storage space provided by at least portions of the storage devices of the storage system into slices, to subdivide the slices into source slices and target slices, and to replicate a source storage object associated with at least one of the source slices to a target storage object associated with at least one of the target slices. The source storage object may be associated with at least one of the source slices by, for example, storing the source storage object across portions of the storage devices in designated ones of the source slices.

Abstract: A first storage system in one embodiment participates in a cycle-based asynchronous replication process with multiple additional storage systems. The first storage system establishes replication sessions with respective ones of the additional storage systems for replication of source data. For each of multiple cycles, the first storage system captures a snapshot of the source data for a current cycle, generates differential data between the snapshot and a corresponding snapshot for a previous cycle, and transmits the differential data to the additional storage systems in their respective replication sessions. In conjunction with completion of transmission of the differential data to a given one of the additional storage systems, the corresponding replication session determines whether or not a snapshot of the source data for a subsequent cycle is available. If there is no such snapshot available, the replication session triggers capture of the snapshot of the source data for the subsequent cycle.

Abstract: An apparatus in one embodiment comprises a storage system having a plurality of storage devices configured to store at least a first set of data. The storage system is configured to generate a first signature for the first set of data and to verify equivalence between the first set of data and a second set of data by comparing the first signature to a second signature generated for the second set of data. The first and second sets of data comprise respective first and second sets of pages with each page having a content-based page identifier and a page address, and the first and second signatures are generated as respective functions of the page identifiers and page addresses of the respective first and second sets of pages. The first and second sets of data may comprise respective first and second storage volumes, respective first and second sets of multiple storage volumes, or other sets of data.

Abstract: A computer program product, system, and method for determining one or more slices of a logical address space assigned to replication processor; determining an elapsed time since a start of a replication cycle; determining an expected number of slices that should have been replicated based on the elapsed time; and replicating one or more slices of the logical address space in response to determining the expected number of slices that should have been replicated is less than an actual number of slices replicated by the replication processor within the replication cycle.

Abstract: A target storage system in one embodiment receives from a source storage system a plurality of content-based signatures of respective data pages of a storage object that is subject to replication from the source storage system to the target storage system. For a given one of the received content-based signatures having a particular logical address, the target storage system compares at least a portion of the received content-based signature with a particular one of a plurality of entries of an address-to-signature table maintained by the target storage system.

Abstract: A system, computer program product, and computer-executable method of providing a layout-independent cryptographic stamp of a distributed data set from a data storage system, the system, computer program product, and computer-executable method comprising receiving a request for a cryptographic stamp of the distributed data set, creating a hash of each slice of the distributed data set, and using each hash from each slice of the distribute data set to create the cryptographic stamp of the distributed data set.

Abstract: An apparatus in one embodiment comprises a storage system having a plurality of storage devices configured to store at least a first set of data. The storage system is configured to generate a first signature for the first set of data and to verify equivalence between the first set of data and a second set of data by comparing the first signature to a second signature generated for the second set of data. The first and second sets of data comprise respective first and second sets of pages with each page having a content-based page identifier and a page address, and the first and second signatures are generated as respective functions of the page identifiers and page addresses of the respective first and second sets of pages. The first and second sets of data may comprise respective first and second storage volumes, respective first and second sets of multiple storage volumes, or other sets of data.

Abstract: A first storage system in one illustrative embodiment is configured to participate in a replication process with a second storage system. A first processing module of a distributed storage controller of the first storage system detects a replication failure condition for a given write request received from a host device, and provides a corresponding notification to a second processing module of the distributed storage controller. The second processing module, responsive to receipt of the notification, instructs the first processing module and a plurality of additional processing modules of a same type as the first processing module to suspend generation of replication acknowledgments for write requests received from the host device. Responsive to receipt of confirmation from the first and additional processing modules of their suspended generation of replication acknowledgements, the second processing module instructs the first and additional processing modules to terminate the replication process.

Abstract: A computer program product, system, and method for visiting each node of a snapshot tree within a content-based storage system having a plurality of volumes and/or snapshots; for each node, scanning an address-to-hash (A2H) table to calculate one or more resource usage metrics, wherein the A2H tables map logical I/O addresses to chunk hashes; and determining, based on the resource usage metrics, an amount of memory and/or disk capacity that would be freed by deleting one or more of the volumes and/or snapshots.

Abstract: A first storage system in one illustrative embodiment is configured to participate in a replication process with a second storage system. In conjunction with a synchronous replication mode of the replication process, a first processing module of a distributed storage controller of the first storage system is configured to write one or more data pages in the first storage system in accordance with a write request received from a host device, to send a corresponding replication write request to the second storage system, to determine whether or not the one or more data pages have been successfully replicated to the second storage system, and to update content-based signature mapping information of the one or more data pages responsive to receipt of an indication of successful replication. Responsive to a determination that the write request was received prior to initiation of the synchronous replication mode, an asynchronous-to-synchronous transition cycle scan operation is restarted.

Abstract: A computer program product, system, and method for calculating a resource usage metric over each node of a snapshot tree within a content-based storage system having a plurality of volumes and/or snapshots and generating a visualization of the snapshot tree using the calculated resource usage metrics.

Abstract: Described embodiments provide systems and processes for performing data replication in a storage system. The data replication operation replicates data from at least one source device to at least one target device of the storage system. A link capacity of a link between at least one source device and at least one target device is determined. Processor overhead associated with one or more data compression processes, and one or more operating conditions of the storage system are determined. Based at least at least in part upon the determined link capacity, the determined processor overhead, and the determined one or more operating conditions, one or more settings of a data replication operation of the storage system are adapted. The data replication operation is performed according to the adapted one or more settings.

Abstract: Described embodiments provide systems and processes for performing a data replication process in a storage system. A current asynchronous replication cycle is initiated at a time-based interval based upon a replication policy of the storage system to replicate data from at least one source device to at least one target device. For the current asynchronous replication cycle, it is determined whether data stored on portions of the source device has changed from a previous asynchronous replication cycle. A new replica of the source device is generated if data stored on the source device has changed from the previous asynchronous replication cycle. The new replica is transferred to the target device. The current asynchronous replication cycle is completed and the replication policy of the storage system is satisfied without generating the new replica if data stored on the source device has not changed from the previous asynchronous replication cycle.

Abstract: A system, computer program product, and computer-executable method of managing replication within a data storage system, the system, computer program product, and computer-executable method including receiving an error related to a replication session within the data storage system, analyzing the error, based on the analysis, determining whether to retry the replication session, upon a positive determination, calculating a first time interval for the replication session, and retrying the replication session upon completion of the first time interval.

Abstract: In one aspect, a method includes selecting a C-module; sending a write from a host to the selected C-module; selecting a D-module to commit a page related to the write; selecting a R-module to transmit data from the write to the target; writing the data from the write to target location; and writing the data to an address-to-hash table after acknowledgement that the data has been written to the target location and after the D-module acknowledges that the page is committed.

Abstract: Described embodiments may provide systems and processes for migrating a replica hierarchy from at least one source device to at least one target device in a storage system. A configuration of the replica hierarchy is migrated, one or more internal nodes of the replica hierarchy are migrated, and one or more leaf nodes of the replica hierarchy are migrated. A cutover operation is performed by deactivating the at least one source device associated with the included replica hierarchy.

Abstract: In one aspect, a method includes splitting empty RAID stripes into sub-stripes and storing pages into the sub-stripes based on a compressibility score. In another aspect, a method includes reading pages from 1-stripes, storing compressed data in a temporary location, reading multiple stripes, determining compressibility score for each stripe and filling stripes based on the compressibility score. In a further aspect, a method includes scanning a dirty queue in a system cache, compressing pages ready for destaging, combining compressed pages in to one aggregated page, writing one aggregated page to one stripe and storing pages with same compressibility score in a stripe.

Abstract: In one aspect, a method includes merging a first consistency group (CG) with a second CG on a source side of a replication system and merging a third CG with a fourth CG on the target side of the replication system. The first CG and the third CG form a first replication pair (RP) and the second CG and the fourth CG form a second RP. The merging includes changing a replication policy of the first RP to be equal to a retention policy of the second RP, waiting for the first RP and the second RP to stop data transfer, terminating replication of the first RP after the data transfer stopped, updating the first RP and second RP at the source side, updating the first RP and second RP at the target side and resuming replication using the second RP.

Abstract: Maintaining a set of extents corresponding to a portion of an initial logical volume that is to be copied includes initializing a table having entries corresponding to different portions of the initial logical volume, where each of the entries is initialized with a first value, following initializing the table, providing a second value different from the first value to an entry in the table corresponding to a portion of the initial logical volume to which a write operation is performed and establishing the set of extents, where the first value is provided to entries in the table that correspond to portions of the initial logical device indicated by the extents. Data of the initial logical volume corresponding to the set of extents may be copied to at least one other logical volume.