Abstract: An apparatus in one embodiment comprises at least one processing device comprising a processor coupled to a memory. The processing device is configured to detect an error relating to storage of a given data page in a first storage system, and to send a message to at least one additional storage system, the message containing a hash digest of the given data page. The processing device is further configured to receive from the additional storage system responsive to the message a recovery data page identified by the additional storage system as having the same hash digest as the given data page. The recovery data page received from the additional storage system is verified by computing a hash digest of the recovery data page and comparing the computed hash digest to the hash digest of the given data page. Separate instances of the message containing the hash digest of the given data page may be sent to each of a plurality of additional storage systems.

Abstract: A first storage system sends a clock synchronization message to a second storage system. The first storage system records a first value of a local time in the first storage system in conjunction with sending the clock synchronization message, and records a second value of the local time in the first storage system in conjunction with receipt of a response to the clock synchronization message from the second storage system. The response comprises a value of a local time in the second storage system. The first storage system computes an estimate of a difference between the local times using the recorded first and second values of the local time in the first storage system and the received value of the local time in the second storage system, and synchronizes the local time in the first storage system with the local time in the second storage using the computed estimate.

Abstract: A method, computer program product, and computer system for preparing, by a computing device, for migration of data from a source to a target. Hash values of the data may be sorted at the source. The data may be migrated from the source to the target according to how the data was sorted at the source.

Abstract: A processing device identifies a first snapshot to be split from a first snapshot group, generates a second snapshot of the first snapshot, continues write operations to the first snapshot, copies the second snapshot to a storage volume of a second snapshot group, and computes a differential between the first and second snapshots. Responsive to the differential between the first and second snapshots being above a specified threshold, an additional snapshot of the first snapshot is generated, a differential is computed between the additional snapshot and a previous snapshot of the first snapshot, and if necessary the generating of an additional snapshot and the computing of a differential are repeated one or more additional times, until the differential is at or below the specified threshold. The processing device updates the storage volume based at least in part on one or more of the computed differentials.

Abstract: An apparatus includes at least one processing device comprising a processor coupled to a memory, with the processing device being configured to identify a first storage volume of a first snapshot group of a storage system, to identify a second storage volume that is not part of the first snapshot group of the storage system but contains at least a threshold amount of matching data relative to the first storage volume, and to merge the second storage volume into the first snapshot group. The processing device illustratively comprises a storage controller of the storage system. The storage system may be implemented as a clustered storage system comprising a plurality of storage nodes. Each storage node may comprise a set of processing modules of a distributed storage controller of the clustered storage system.

Abstract: An apparatus obtains a set of content-based signatures for respective data pages of at least a portion of at least one storage volume replicated from a source storage system to a target storage system, issues a write for the set of content-based signatures to the target storage system, and reads from a designated location in the target storage system information indicating for each of the content-based signatures whether or not the corresponding data page is present in the target storage system. For one or more data pages not present in the target storage system, the apparatus writes the one or more data pages to respective logical addresses of the replicated storage volume in the target storage system. The issuing of a write, the reading from the designated location, and the writing of the one or more data pages are illustratively performed utilizing respective commands of a standard storage command protocol.

Abstract: A storage system in one embodiment comprises a plurality of storage devices and a storage controller. The storage system is configured to participate as a target storage system in a replication process with a source storage system. In conjunction with the replication process, the target storage system is configured to receive from the source storage system replication data for at least one storage volume subject to replication from the source storage system to the target storage system, to generate a first snapshot for the storage volume, to monitor additional replication data received from the source storage system for the storage volume after generation of the first snapshot, and responsive to the monitored additional replication data satisfying one or more specified conditions, to perform at least one of the following operations: (i) generating a subsequent snapshot for the storage volume; and (ii) marking the first snapshot with a priority indicator.

Abstract: Techniques for determining unique ownership of data blocks includes selecting a first data block referenced by a first logical address of a first logical device, wherein first metadata for the first data block includes a reference count and a result used in determining sole unique ownership of the first data block; determining C1, an expected value of the result of the first metadata when the first logical device is a sole unique owner of the first data block; and performing first processing that determines whether the first logical device is the sole unique owner of the first data block. The first processing includes: determining whether C1 equals a current value of the result of the first metadata; and determining that the first logical device is the sole unique owner of the first data block if C1 equals the current value of the result of the first metadata.

Abstract: First information for a first event of a computer system is captured, including first event parameters. A first event key is generated, based on the first event parameters. The first information and first key are both stored as a first event in a storage structure, in which the first event key indexes the first event and the captured first information. When second information is captured for a second event, a second event key is generated based on second event parameters of the captured second event. If the second event key matches the first event key, then the first event stored in the event collection system is dynamically updated to store the second event information as part of the first event, to minimize additional storage space needed in the storage structure for the second event.

Abstract: A storage system comprises a plurality of storage nodes each comprising one or more storage devices and a processor coupled to a memory. The storage system is configured to store data blocks across the storage devices of the storage nodes utilizing a redundant array of independent disks (RAID) arrangement. At least a given one of the storage nodes is configured to store a plurality of RAID metadata bitmaps in persistent storage of the storage node so as to be available for a recovery operation in the event of a detected failure, to identify a particular subset of the RAID metadata bitmaps to be updated in conjunction with an additional operation other than the recovery operation, and to temporarily store the identified subset of the RAID metadata bitmaps in the memory of the storage node in a manner determined based at least in part on an operation type of the additional operation.

Abstract: Techniques for processing I/O operations include receiving an I/O operation that accesses a target location. Metadata (MD) pages are accessed in a consecutive order to access the target location in a user data (UD) page. First processing is performed by first code. The first processing includes determining that a first MD page is not in cache; responsive to determining the first MD page is not in the cache, issuing a forwarding read command to a component to obtain pages including the first MD page and one or more other MD pages subsequent to the first MD page in the consecutive order; and receiving a response to the forwarding read command that includes the requested pages.

Abstract: A distributed storage system comprises a first module and a second module. The first module processes read requests for an address range, to send to the second module. The first module receives an address associated with a read request for a data page stored on the second module. A method searches a table on the first module for a content-based signature of the data page based on the address and provides the data page from a first module read cache if the content-based signature is in the read cache, where content-based signatures in the table are associated with the address range.

Abstract: In one aspect, implementing enhanced QoS for multiple replication sessions in a replication setup includes, for each of a number of replication sessions simultaneously implemented via the storage system, determining an assigned priority level and calculating a corresponding resource profile. The resource profile specifies a minimum required amount of bandwidth and a minimum amount of input/output (IO) operations for the replication session. An aspect also includes determining available system resources for an aggregate of the replication sessions. The available system resources indicate a maximum available amount of bandwidth and a maximum available IO rate across the storage system. An aspect further includes apportioning resources among the replication sessions as a function of collective priority levels, resource profiles, and the available system resources.

Abstract: A processing device identifies a first snapshot to be split from a first snapshot group, generates a second snapshot of the first snapshot, continues write operations to the first snapshot, copies the second snapshot to a storage volume of a second snapshot group, and computes a differential between the first and second snapshots. Responsive to the differential between the first and second snapshots being above a specified threshold, an additional snapshot of the first snapshot is generated, a differential is computed between the additional snapshot and a previous snapshot of the first snapshot, and if necessary the generating of an additional snapshot and the computing of a differential are repeated one or more additional times, until the differential is at or below the specified threshold. The processing device updates the storage volume based at least in part on one or more of the computed differentials.

Abstract: An aspect includes generating a checkpoint for a storage system containing an image for a point in time. An aspect also includes storing, in a reserved area, volume configuration data corresponding to volumes for the point in time, layers of metadata and physical data for the point in time. An aspect further includes creating consistent snapshots for the volumes, destaging a control module journal and persisting a hash tree and dirty tree metadata, destaging a code cache, dumping hash metadata and physical layout metadata to a separate location in the storage and enabling new metadata updates to a default location. An aspect also includes redirecting new data and metadata IOS to stripes reserved during preparation of the separate location relating to the checkpoint and protecting checkpointed data and metadata, and generating a consistent checkpoint copy of a management module repository in the reserved area of storage.

Abstract: In one aspect, provenance-based replication includes assigning a GUID to a first snap tree of a first storage array and another GUID to a second snap tree of a second storage array. The trees are peers of each other with respect to at least one volume replicated between the arrays. For each volume in the first array that is replicated to a volume in the second array, an aspect includes assigning a volume pairing identifier common to both volumes. Upon determining data for a volume (V1) in the first array has been lost/corrupted, an aspect includes identifying the peer tree from the GUID and using the pairing ID of V1 to search the peer tree for a volume (V2) in the second array, retrieving data for V2, computing a delta between the data of V1 and the data of V2, and reconstructing the lost/corrupted data for V1 using the delta.

Abstract: In one aspect, implementing enhanced QoS for multiple replication sessions in a replication setup includes, for each of a number of replication sessions simultaneously implemented via the storage system, determining an assigned priority level and calculating a corresponding resource profile. The resource profile specifies a minimum required amount of bandwidth and a minimum amount of input/output (IO) operations for the replication session. An aspect also includes determining available system resources for an aggregate of the replication sessions. The available system resources indicate a maximum available amount of bandwidth and a maximum available IO rate across the storage system. An aspect further includes apportioning resources among the replication sessions as a function of collective priority levels, resource profiles, and the available system resources.

Abstract: An apparatus comprises at least one processing device comprising a processor coupled to a memory that is configured to initiate a read data request utilizing a logical address of a content addressable storage system that maps to a physical address comprising an offset on a storage device that internally maps the offset to a first sector. The processing device is also configured to determine a health of the first sector responsive to the read data request failing, to recover data stored in the first sector responsive to the first sector being a bad sector, and to overwrite the recovered data to the logical address while maintaining the mapping to the physical address by directing a write of the recovered data to the offset to update the internal mapping of the offset in the storage device to a new physical location corresponding to a second sector different than the first sector.

Abstract: An apparatus includes at least one processing device comprising a processor coupled to a memory, with the processing device being configured to identify a first storage volume of a first snapshot group of a storage system, to identify a second storage volume that is not part of the first snapshot group of the storage system but contains at least a threshold amount of matching data relative to the first storage volume, and to merge the second storage volume into the first snapshot group. The processing device illustratively comprises a storage controller of the storage system. The storage system may be implemented as a clustered storage system comprising a plurality of storage nodes. Each storage node may comprise a set of processing modules of a distributed storage controller of the clustered storage system.

Abstract: In one aspect, implementing a link selection protocol in a replication setup includes sending, by a control module to a selected routing module of a plurality of routing modules, an IO request and IO requirements to process the request. The IO requirements include an amount of data subject to the replication IO request and a latency requirement subject to the replication IO request. A further aspect includes comparing, by the selected routing module, the IO requirements to link status information of each of a plurality of links; selecting, by the selected routing module, one of the links assigned to the selected routing module as a function of the IO requirements and the link status information; and executing the IO request over the selected one of the links.